TY  - JOUR
AU  - Ostojić, Bojana
AU  - Stanković, Branislav
AU  - Đorđević, Dragana
AU  - Schwerdtfeger, Peter
PY  - 2022
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/5350
AB  - CO2 capture, conversion and storage belong to the holy grail of environmental science. We therefore explore an important photochemical hydride transfer reaction of benzimidazoline derivatives with CO2 in a polar solvent (dimethylsulfoxide) by quantum-chemical methods. While the excited electronic state undergoing hydride transfer to formate (HCOO−) shows a higher reaction path barrier compared to the ground state, a charge-transfer can occur in the near-UV region with nearly barrierless access to the products involving a conical intersection between both electronic states. Such radiationless decay through the hydride transfer reaction and formation of HCCO−via excited electronic states in suitable organic compounds opens the way for future photochemical CO2 reduction. We provide a detailed analysis for the chemical CO2 reduction to the formate anion for 15 different benzimidazoline derivatives in terms of thermodynamic hydricities (ΔGH), activation free energies (ΔG‡HT), and reaction free energies (ΔGrxn) for the chosen solvent dimethylsulfoxide at the level of density functional theory. The calculated hydricities are in the range from 35.0 to 42.0 kcal mol−1i.e. the species possess strong hydride donor abilities required for the CO2 reduction to formate, characterized by relatively low activation free energies between 18.5 and 22.2 kcal mol−1. The regeneration of the benzimidazoline can be achieved electrochemically.
PB  - Elsevier
T2  - Physical Chemistry Chemical Physics
T1  - Light-driven reduction of CO2: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives
VL  - 24
IS  - 34
SP  - 20357
EP  - 20370
DO  - 10.1039/d2cp02867k
ER  - 

@article{
author = "Ostojić, Bojana and Stanković, Branislav and Đorđević, Dragana and Schwerdtfeger, Peter",
year = "2022",
abstract = "CO2 capture, conversion and storage belong to the holy grail of environmental science. We therefore explore an important photochemical hydride transfer reaction of benzimidazoline derivatives with CO2 in a polar solvent (dimethylsulfoxide) by quantum-chemical methods. While the excited electronic state undergoing hydride transfer to formate (HCOO−) shows a higher reaction path barrier compared to the ground state, a charge-transfer can occur in the near-UV region with nearly barrierless access to the products involving a conical intersection between both electronic states. Such radiationless decay through the hydride transfer reaction and formation of HCCO−via excited electronic states in suitable organic compounds opens the way for future photochemical CO2 reduction. We provide a detailed analysis for the chemical CO2 reduction to the formate anion for 15 different benzimidazoline derivatives in terms of thermodynamic hydricities (ΔGH), activation free energies (ΔG‡HT), and reaction free energies (ΔGrxn) for the chosen solvent dimethylsulfoxide at the level of density functional theory. The calculated hydricities are in the range from 35.0 to 42.0 kcal mol−1i.e. the species possess strong hydride donor abilities required for the CO2 reduction to formate, characterized by relatively low activation free energies between 18.5 and 22.2 kcal mol−1. The regeneration of the benzimidazoline can be achieved electrochemically.",
publisher = "Elsevier",
journal = "Physical Chemistry Chemical Physics",
title = "Light-driven reduction of CO2: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives",
volume = "24",
number = "34",
pages = "20357-20370",
doi = "10.1039/d2cp02867k"
}

Ostojić, B., Stanković, B., Đorđević, D.,& Schwerdtfeger, P.. (2022). Light-driven reduction of CO2: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives. in Physical Chemistry Chemical Physics
Elsevier., 24(34), 20357-20370.
https://doi.org/10.1039/d2cp02867k

Ostojić B, Stanković B, Đorđević D, Schwerdtfeger P. Light-driven reduction of CO2: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives. in Physical Chemistry Chemical Physics. 2022;24(34):20357-20370.
doi:10.1039/d2cp02867k .

Ostojić, Bojana, Stanković, Branislav, Đorđević, Dragana, Schwerdtfeger, Peter, "Light-driven reduction of CO2: thermodynamics and kinetics of hydride transfer reactions in benzimidazoline derivatives" in Physical Chemistry Chemical Physics, 24, no. 34 (2022):20357-20370,
https://doi.org/10.1039/d2cp02867k . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Schwerdtfeger, Peter
AU  - Đorđević, Dragana
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4284
AB  - The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-cross-over" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.
PB  - Elsevier Science Inc, New York
T2  - Journal of Inorganic Biochemistry
T1  - Modeling the hydrogen sulfide binding to heme
VL  - 184
SP  - 108
EP  - 114
DO  - 10.1016/j.jinorgbio.2018.04.012
ER  - 

@article{
author = "Ostojić, Bojana and Schwerdtfeger, Peter and Đorđević, Dragana",
year = "2018",
abstract = "The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-cross-over" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.",
publisher = "Elsevier Science Inc, New York",
journal = "Journal of Inorganic Biochemistry",
title = "Modeling the hydrogen sulfide binding to heme",
volume = "184",
pages = "108-114",
doi = "10.1016/j.jinorgbio.2018.04.012"
}

Ostojić, B., Schwerdtfeger, P.,& Đorđević, D.. (2018). Modeling the hydrogen sulfide binding to heme. in Journal of Inorganic Biochemistry
Elsevier Science Inc, New York., 184, 108-114.
https://doi.org/10.1016/j.jinorgbio.2018.04.012

Ostojić B, Schwerdtfeger P, Đorđević D. Modeling the hydrogen sulfide binding to heme. in Journal of Inorganic Biochemistry. 2018;184:108-114.
doi:10.1016/j.jinorgbio.2018.04.012 .

Ostojić, Bojana, Schwerdtfeger, Peter, Đorđević, Dragana, "Modeling the hydrogen sulfide binding to heme" in Journal of Inorganic Biochemistry, 184 (2018):108-114,
https://doi.org/10.1016/j.jinorgbio.2018.04.012 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Schwerdtfeger, Peter
AU  - Đorđević, Dragana
PY  - 2018
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2286
AB  - The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-cross-over" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.
PB  - Elsevier Science Inc, New York
T2  - Journal of Inorganic Biochemistry
T1  - Modeling the hydrogen sulfide binding to heme
VL  - 184
SP  - 108
EP  - 114
DO  - 10.1016/j.jinorgbio.2018.04.012
ER  - 

@article{
author = "Ostojić, Bojana and Schwerdtfeger, Peter and Đorđević, Dragana",
year = "2018",
abstract = "The binding of hydrogen sulfide to a model heme compound is investigated by coupled-cluster singles-doubles augmented by a perturbative triple excitations, CCSD(T), and density functional theory, DFT. The minimum energy path for the H2S addition to an isolated heme center of the heme protein is evaluated by adopting as a model the heme compound FeP(Im) (P = porphyrin; Im = imidazole). The FeP(Im)-H2S aduct is bound by 13.7 kcal/mol at the CCSD(T) level of theory. Relaxed potential energy curves for the lowest lying spin states of the H2S to FeP(Im) binding using DFT reveal that the binding process is associated with a "double spin-cross-over" reaction with the existence of long-distance van der Waals minima only 5-7 kcal/mol above the FeP(Im)-H2S ground state. The fact that the energy of the singlet ground state of FeP(Im)-H2S is so close in energy to the dissociation products FeP(Im) + H2S points towards the reversibility of the H2S adsorption/desorption process in biochemical reactions.",
publisher = "Elsevier Science Inc, New York",
journal = "Journal of Inorganic Biochemistry",
title = "Modeling the hydrogen sulfide binding to heme",
volume = "184",
pages = "108-114",
doi = "10.1016/j.jinorgbio.2018.04.012"
}

Ostojić, B., Schwerdtfeger, P.,& Đorđević, D.. (2018). Modeling the hydrogen sulfide binding to heme. in Journal of Inorganic Biochemistry
Elsevier Science Inc, New York., 184, 108-114.
https://doi.org/10.1016/j.jinorgbio.2018.04.012

Ostojić B, Schwerdtfeger P, Đorđević D. Modeling the hydrogen sulfide binding to heme. in Journal of Inorganic Biochemistry. 2018;184:108-114.
doi:10.1016/j.jinorgbio.2018.04.012 .

Ostojić, Bojana, Schwerdtfeger, Peter, Đorđević, Dragana, "Modeling the hydrogen sulfide binding to heme" in Journal of Inorganic Biochemistry, 184 (2018):108-114,
https://doi.org/10.1016/j.jinorgbio.2018.04.012 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Schwerdtfeger, Peter
AU  - Bunker, P. R.
AU  - Jensen, Per
PY  - 2016
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4311
AB  - We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH2 and BiH2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption. For the heavier dihydride BiH2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Journal of Molecular Spectroscopy
T1  - An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2
VL  - 330
SP  - 130
EP  - 141
DO  - 10.1016/j.jms.2016.03.004
ER  - 

@article{
author = "Ostojić, Bojana and Schwerdtfeger, Peter and Bunker, P. R. and Jensen, Per",
year = "2016",
abstract = "We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH2 and BiH2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption. For the heavier dihydride BiH2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Journal of Molecular Spectroscopy",
title = "An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2",
volume = "330",
pages = "130-141",
doi = "10.1016/j.jms.2016.03.004"
}

Ostojić, B., Schwerdtfeger, P., Bunker, P. R.,& Jensen, P.. (2016). An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2. in Journal of Molecular Spectroscopy
Academic Press Inc Elsevier Science, San Diego., 330, 130-141.
https://doi.org/10.1016/j.jms.2016.03.004

Ostojić B, Schwerdtfeger P, Bunker PR, Jensen P. An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2. in Journal of Molecular Spectroscopy. 2016;330:130-141.
doi:10.1016/j.jms.2016.03.004 .

Ostojić, Bojana, Schwerdtfeger, Peter, Bunker, P. R., Jensen, Per, "An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2" in Journal of Molecular Spectroscopy, 330 (2016):130-141,
https://doi.org/10.1016/j.jms.2016.03.004 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Schwerdtfeger, Peter
AU  - Bunker, P. R.
AU  - Jensen, Per
PY  - 2016
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1904
AB  - We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH2 and BiH2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption. For the heavier dihydride BiH2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Journal of Molecular Spectroscopy
T1  - An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2
VL  - 330
SP  - 130
EP  - 141
DO  - 10.1016/j.jms.2016.03.004
ER  - 

@article{
author = "Ostojić, Bojana and Schwerdtfeger, Peter and Bunker, P. R. and Jensen, Per",
year = "2016",
abstract = "We present the results of ab initio calculations for the lower electronic states of the Group 15 (pnictogen) dihydrides, SbH2 and BiH2. For each of these molecules the two lowest electronic states become degenerate at linearity and are therefore subject to the Renner effect. Spin-orbit coupling is also strong in these two heavy-element containing molecules. For the lowest two electronic states of SbH2, we construct the three dimensional potential energy surfaces and corresponding dipole moment and transition moment surfaces by multi-reference configuration interaction techniques. Including both the Renner effect and spin-orbit coupling, we calculate term values and simulate the rovibrational and rovibronic spectra of SbH2. Excellent agreement is obtained with the results of matrix isolation infrared spectroscopic studies and with gas phase electronic spectroscopic studies in absorption. For the heavier dihydride BiH2 we calculate bending potential curves and the spin-orbit coupling constant for comparison. For SbH2 we further study the local mode vibrational behavior and the formation of rovibronic energy level clusters in high angular momentum states.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Journal of Molecular Spectroscopy",
title = "An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2",
volume = "330",
pages = "130-141",
doi = "10.1016/j.jms.2016.03.004"
}

Ostojić, B., Schwerdtfeger, P., Bunker, P. R.,& Jensen, P.. (2016). An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2. in Journal of Molecular Spectroscopy
Academic Press Inc Elsevier Science, San Diego., 330, 130-141.
https://doi.org/10.1016/j.jms.2016.03.004

Ostojić B, Schwerdtfeger P, Bunker PR, Jensen P. An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2. in Journal of Molecular Spectroscopy. 2016;330:130-141.
doi:10.1016/j.jms.2016.03.004 .

Ostojić, Bojana, Schwerdtfeger, Peter, Bunker, P. R., Jensen, Per, "An ab initio study of SbH2 and BiH2: The Renner effect, spin-orbit coupling, local mode vibrations and rovibronic energy level clustering in SbH2" in Journal of Molecular Spectroscopy, 330 (2016):130-141,
https://doi.org/10.1016/j.jms.2016.03.004 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Jensen, Per
AU  - Schwerdtfeger, Peter
AU  - Bunker, P. R.
PY  - 2014
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/3167
AB  - This ab initio study of Group 2 M2O hypermetallic oxides focuses mainly on the two heaviest members, Ba20 and Ra20. In accordance with previous studies in our group on the Be, Mg, Ca and Sr hypermetallic oxides, we find that the Ba0Ba and Ra0Ra molecules have a linear X1Eg+ ground electronic state and a very low lying first excited 5/3Eu+ triplet electronic state. Special attention is placed on calculating and understanding how the singlet-triplet splitting and singlet-triplet interaction strength vary down the series. The calculations reveal that MgOMg shows the largest singlet-triplet splitting and does not fit into the overall trend down the Group 2 series of elements. However, in all cases the extent of the singlettriplet interaction between vibronic levels of the (X) over tilde and (alpha) over tilde states is very small. On the experimental side, there is literature evidence for the formation of electronically excited Ba2O in oxidation reactions of barium dimers, and our calculations of excited singlet and triplet state energies support that assignment.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Journal of Molecular Spectroscopy
T1  - Singlet-triplet interaction in Group 2 M2O hypermetallic oxides
VL  - 301
SP  - 20
EP  - 24
DO  - 10.1016/j.jms.2014.05.003
ER  - 

@article{
author = "Ostojić, Bojana and Jensen, Per and Schwerdtfeger, Peter and Bunker, P. R.",
year = "2014",
abstract = "This ab initio study of Group 2 M2O hypermetallic oxides focuses mainly on the two heaviest members, Ba20 and Ra20. In accordance with previous studies in our group on the Be, Mg, Ca and Sr hypermetallic oxides, we find that the Ba0Ba and Ra0Ra molecules have a linear X1Eg+ ground electronic state and a very low lying first excited 5/3Eu+ triplet electronic state. Special attention is placed on calculating and understanding how the singlet-triplet splitting and singlet-triplet interaction strength vary down the series. The calculations reveal that MgOMg shows the largest singlet-triplet splitting and does not fit into the overall trend down the Group 2 series of elements. However, in all cases the extent of the singlettriplet interaction between vibronic levels of the (X) over tilde and (alpha) over tilde states is very small. On the experimental side, there is literature evidence for the formation of electronically excited Ba2O in oxidation reactions of barium dimers, and our calculations of excited singlet and triplet state energies support that assignment.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Journal of Molecular Spectroscopy",
title = "Singlet-triplet interaction in Group 2 M2O hypermetallic oxides",
volume = "301",
pages = "20-24",
doi = "10.1016/j.jms.2014.05.003"
}

Ostojić, B., Jensen, P., Schwerdtfeger, P.,& Bunker, P. R.. (2014). Singlet-triplet interaction in Group 2 M2O hypermetallic oxides. in Journal of Molecular Spectroscopy
Academic Press Inc Elsevier Science, San Diego., 301, 20-24.
https://doi.org/10.1016/j.jms.2014.05.003

Ostojić B, Jensen P, Schwerdtfeger P, Bunker PR. Singlet-triplet interaction in Group 2 M2O hypermetallic oxides. in Journal of Molecular Spectroscopy. 2014;301:20-24.
doi:10.1016/j.jms.2014.05.003 .

Ostojić, Bojana, Jensen, Per, Schwerdtfeger, Peter, Bunker, P. R., "Singlet-triplet interaction in Group 2 M2O hypermetallic oxides" in Journal of Molecular Spectroscopy, 301 (2014):20-24,
https://doi.org/10.1016/j.jms.2014.05.003 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Jensen, Per
AU  - Schwerdtfeger, Peter
AU  - Bunker, P. R.
PY  - 2014
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1559
AB  - This ab initio study of Group 2 M2O hypermetallic oxides focuses mainly on the two heaviest members, Ba20 and Ra20. In accordance with previous studies in our group on the Be, Mg, Ca and Sr hypermetallic oxides, we find that the Ba0Ba and Ra0Ra molecules have a linear X1Eg+ ground electronic state and a very low lying first excited 5/3Eu+ triplet electronic state. Special attention is placed on calculating and understanding how the singlet-triplet splitting and singlet-triplet interaction strength vary down the series. The calculations reveal that MgOMg shows the largest singlet-triplet splitting and does not fit into the overall trend down the Group 2 series of elements. However, in all cases the extent of the singlettriplet interaction between vibronic levels of the (X) over tilde and (alpha) over tilde states is very small. On the experimental side, there is literature evidence for the formation of electronically excited Ba2O in oxidation reactions of barium dimers, and our calculations of excited singlet and triplet state energies support that assignment.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Journal of Molecular Spectroscopy
T1  - Singlet-triplet interaction in Group 2 M2O hypermetallic oxides
VL  - 301
SP  - 20
EP  - 24
DO  - 10.1016/j.jms.2014.05.003
ER  - 

@article{
author = "Ostojić, Bojana and Jensen, Per and Schwerdtfeger, Peter and Bunker, P. R.",
year = "2014",
abstract = "This ab initio study of Group 2 M2O hypermetallic oxides focuses mainly on the two heaviest members, Ba20 and Ra20. In accordance with previous studies in our group on the Be, Mg, Ca and Sr hypermetallic oxides, we find that the Ba0Ba and Ra0Ra molecules have a linear X1Eg+ ground electronic state and a very low lying first excited 5/3Eu+ triplet electronic state. Special attention is placed on calculating and understanding how the singlet-triplet splitting and singlet-triplet interaction strength vary down the series. The calculations reveal that MgOMg shows the largest singlet-triplet splitting and does not fit into the overall trend down the Group 2 series of elements. However, in all cases the extent of the singlettriplet interaction between vibronic levels of the (X) over tilde and (alpha) over tilde states is very small. On the experimental side, there is literature evidence for the formation of electronically excited Ba2O in oxidation reactions of barium dimers, and our calculations of excited singlet and triplet state energies support that assignment.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Journal of Molecular Spectroscopy",
title = "Singlet-triplet interaction in Group 2 M2O hypermetallic oxides",
volume = "301",
pages = "20-24",
doi = "10.1016/j.jms.2014.05.003"
}

Ostojić, B., Jensen, P., Schwerdtfeger, P.,& Bunker, P. R.. (2014). Singlet-triplet interaction in Group 2 M2O hypermetallic oxides. in Journal of Molecular Spectroscopy
Academic Press Inc Elsevier Science, San Diego., 301, 20-24.
https://doi.org/10.1016/j.jms.2014.05.003

Ostojić B, Jensen P, Schwerdtfeger P, Bunker PR. Singlet-triplet interaction in Group 2 M2O hypermetallic oxides. in Journal of Molecular Spectroscopy. 2014;301:20-24.
doi:10.1016/j.jms.2014.05.003 .

Ostojić, Bojana, Jensen, Per, Schwerdtfeger, Peter, Bunker, P. R., "Singlet-triplet interaction in Group 2 M2O hypermetallic oxides" in Journal of Molecular Spectroscopy, 301 (2014):20-24,
https://doi.org/10.1016/j.jms.2014.05.003 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Jensen, Per
AU  - Schwerdtfeger, Peter
AU  - Bunker, P. R.
PY  - 2013
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1254
AB  - In accordance with previous studies in our group on Be, Mg, and Ca hypermetallic oxides, we find that SrOSr has a linear (X) over tilde (1)Sigma(+)(g) ground electronic state and a very low lying first excited (a) over tilde (3)Sigma(+)(u) triplet electronic state. No gas-phase spectrum of this molecule has been assigned yet, and to encourage and assist in its discovery we present a complete ab initio simulation, with absolute intensities, of the infrared absorption spectrum for both electronic states. The three-dimensional potential energy surfaces and the electric dipole moment surfaces of the (X) over tilde (1)Sigma(+)(g) and (a) over tilde (3)Sigma(+)(u) electronic states are calculated using a multireference configuration interaction (MRCISD) approach in combination with internally contracted rnultireference perturbation theory (RS2C) based on complete active space self consistent field (CASSCF) wave functions applying a Sadlej pVTZ basis set for both O and Sr and the Stuttgart relativistic small core effective core potential for Sr. The infrared spectra are simulated using the MORBID program system. We also calculate vertical excitation energies and transition moments for several excited singlet and triplet electronic states in order to predict the positions and intensities of the most prominent singlet and triplet electronic absorption bands. Finally, for this heavy molecule, we calculate the singlet-triplet interaction matrix elements between close-lying vibronic levels of the (X) over tilde and (a) over tilde electronic states and find them to be,very small.
PB  - American Chemical Society (ACS)
T2  - Journal of Physical Chemistry A
T1  - The Predicted Spectrum and Singlet-Triplet Interaction of the Hypermetallic Molecule SrOSr
VL  - 117
IS  - 39
SP  - 9370
EP  - 9379
DO  - 10.1021/jp310531s
ER  - 

@article{
author = "Ostojić, Bojana and Jensen, Per and Schwerdtfeger, Peter and Bunker, P. R.",
year = "2013",
abstract = "In accordance with previous studies in our group on Be, Mg, and Ca hypermetallic oxides, we find that SrOSr has a linear (X) over tilde (1)Sigma(+)(g) ground electronic state and a very low lying first excited (a) over tilde (3)Sigma(+)(u) triplet electronic state. No gas-phase spectrum of this molecule has been assigned yet, and to encourage and assist in its discovery we present a complete ab initio simulation, with absolute intensities, of the infrared absorption spectrum for both electronic states. The three-dimensional potential energy surfaces and the electric dipole moment surfaces of the (X) over tilde (1)Sigma(+)(g) and (a) over tilde (3)Sigma(+)(u) electronic states are calculated using a multireference configuration interaction (MRCISD) approach in combination with internally contracted rnultireference perturbation theory (RS2C) based on complete active space self consistent field (CASSCF) wave functions applying a Sadlej pVTZ basis set for both O and Sr and the Stuttgart relativistic small core effective core potential for Sr. The infrared spectra are simulated using the MORBID program system. We also calculate vertical excitation energies and transition moments for several excited singlet and triplet electronic states in order to predict the positions and intensities of the most prominent singlet and triplet electronic absorption bands. Finally, for this heavy molecule, we calculate the singlet-triplet interaction matrix elements between close-lying vibronic levels of the (X) over tilde and (a) over tilde electronic states and find them to be,very small.",
publisher = "American Chemical Society (ACS)",
journal = "Journal of Physical Chemistry A",
title = "The Predicted Spectrum and Singlet-Triplet Interaction of the Hypermetallic Molecule SrOSr",
volume = "117",
number = "39",
pages = "9370-9379",
doi = "10.1021/jp310531s"
}

Ostojić, B., Jensen, P., Schwerdtfeger, P.,& Bunker, P. R.. (2013). The Predicted Spectrum and Singlet-Triplet Interaction of the Hypermetallic Molecule SrOSr. in Journal of Physical Chemistry A
American Chemical Society (ACS)., 117(39), 9370-9379.
https://doi.org/10.1021/jp310531s

Ostojić B, Jensen P, Schwerdtfeger P, Bunker PR. The Predicted Spectrum and Singlet-Triplet Interaction of the Hypermetallic Molecule SrOSr. in Journal of Physical Chemistry A. 2013;117(39):9370-9379.
doi:10.1021/jp310531s .

Ostojić, Bojana, Jensen, Per, Schwerdtfeger, Peter, Bunker, P. R., "The Predicted Spectrum and Singlet-Triplet Interaction of the Hypermetallic Molecule SrOSr" in Journal of Physical Chemistry A, 117, no. 39 (2013):9370-9379,
https://doi.org/10.1021/jp310531s . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Bunker, P. R.
AU  - Schwerdtfeger, Peter
AU  - Gertych, Artur
AU  - Jensen, Per
PY  - 2012
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1100
AB  - This study of CaOCa is our third paper in a series on Group 2 alkaline-earth M2O hypermetallic oxides. As with our previous calculations for BeOBe and MgOMg, the ab initio calculations we report here show that CaOCa has a linear 1 Sigma(+)(g) ground electronic state and a very low lying linear (a) over tilde (3)Sigma(+)(u) first excited triplet electronic state. For CaOCa we determine that the singlet-triplet splitting T-e((a) over tilde) = 386 cm(-1). We calculate the three-dimensional potential energy surface, and the electric dipole moment surfaces, of each of the two states using a multireference configuration interaction (MRCISD) approach in combination with internally contracted multireference perturbation theory (RS2C) based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions with a cc-pwCVQZ-DK basis set for Ca and a cc-pCVQZ basis set for O. We simulate the infrared absorption spectra of Ca-40 (OCa)-O-16-Ca-40 in each of these electronic states in order to aid in its eventual spectroscopic characterization.
PB  - Elsevier
T2  - Journal of Molecular Structure
T1  - The predicted infrared spectrum of the hypermetallic molecule CaOCa in its lowest two electronic states (X)over-tilde(1)Sigma(+)(g); and (a)over-tilde(3)Sigma(+)(u)
VL  - 1023
SP  - 101
EP  - 107
DO  - 10.1016/j.molstruc.2012.03.048
ER  - 

@article{
author = "Ostojić, Bojana and Bunker, P. R. and Schwerdtfeger, Peter and Gertych, Artur and Jensen, Per",
year = "2012",
abstract = "This study of CaOCa is our third paper in a series on Group 2 alkaline-earth M2O hypermetallic oxides. As with our previous calculations for BeOBe and MgOMg, the ab initio calculations we report here show that CaOCa has a linear 1 Sigma(+)(g) ground electronic state and a very low lying linear (a) over tilde (3)Sigma(+)(u) first excited triplet electronic state. For CaOCa we determine that the singlet-triplet splitting T-e((a) over tilde) = 386 cm(-1). We calculate the three-dimensional potential energy surface, and the electric dipole moment surfaces, of each of the two states using a multireference configuration interaction (MRCISD) approach in combination with internally contracted multireference perturbation theory (RS2C) based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions with a cc-pwCVQZ-DK basis set for Ca and a cc-pCVQZ basis set for O. We simulate the infrared absorption spectra of Ca-40 (OCa)-O-16-Ca-40 in each of these electronic states in order to aid in its eventual spectroscopic characterization.",
publisher = "Elsevier",
journal = "Journal of Molecular Structure",
title = "The predicted infrared spectrum of the hypermetallic molecule CaOCa in its lowest two electronic states (X)over-tilde(1)Sigma(+)(g); and (a)over-tilde(3)Sigma(+)(u)",
volume = "1023",
pages = "101-107",
doi = "10.1016/j.molstruc.2012.03.048"
}

Ostojić, B., Bunker, P. R., Schwerdtfeger, P., Gertych, A.,& Jensen, P.. (2012). The predicted infrared spectrum of the hypermetallic molecule CaOCa in its lowest two electronic states (X)over-tilde(1)Sigma(+)(g); and (a)over-tilde(3)Sigma(+)(u). in Journal of Molecular Structure
Elsevier., 1023, 101-107.
https://doi.org/10.1016/j.molstruc.2012.03.048

Ostojić B, Bunker PR, Schwerdtfeger P, Gertych A, Jensen P. The predicted infrared spectrum of the hypermetallic molecule CaOCa in its lowest two electronic states (X)over-tilde(1)Sigma(+)(g); and (a)over-tilde(3)Sigma(+)(u). in Journal of Molecular Structure. 2012;1023:101-107.
doi:10.1016/j.molstruc.2012.03.048 .

Ostojić, Bojana, Bunker, P. R., Schwerdtfeger, Peter, Gertych, Artur, Jensen, Per, "The predicted infrared spectrum of the hypermetallic molecule CaOCa in its lowest two electronic states (X)over-tilde(1)Sigma(+)(g); and (a)over-tilde(3)Sigma(+)(u)" in Journal of Molecular Structure, 1023 (2012):101-107,
https://doi.org/10.1016/j.molstruc.2012.03.048 . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Bunker, P. R.
AU  - Schwerdtfeger, Peter
AU  - Assadollahzadeh, B.
AU  - Jensen, Per
PY  - 2011
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/906
AB  - The present study of MgOMg is a continuation of our theoretical work on Group 2 M2O hypermetallic oxides. Previous ab initio calculations have shown that MgOMg has a linear (1)Sigma(+)(g) ground electronic state and a very low lying first excited triplet electronic state that is also linear; the triplet state has (3)Sigma(+)(u) symmetry. No gas phase spectrum of this molecule has been assigned, and here we simulate the infrared absorption spectrum for both states. We calculate the three-dimensional potential energy surface, and the electric dipole moment surfaces, of each of the two states using a multireference configuration interaction (MRCISD) approach based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions with a cc-pCVQZ basis set. A variational MORBID calculation using our potential energy and dipole moment surfaces is performed to determine rovibrational term values and to simulate the infrared absorption spectrum of the two states. We also calculate the dipole polarizability of both states at their equilibrium geometry in order to assist in the interpretation of future beam deflection experiments. Finally, in order to assist in the analysis of the electronic spectrum, we calculate the vertical excitation energies, and electric dipole transition matrix elements, for six excited singlet states and five excited triplet states using the state-average full valence CASSCF-MRCISD/aug-cc-pCVQZ procedure.
PB  - Royal Soc Chemistry, Cambridge
T2  - Physical Chemistry Chemical Physics
T1  - The predicted spectrum of the hypermetallic molecule MgOMg
VL  - 13
IS  - 16
SP  - 7546
EP  - 7553
DO  - 10.1039/c0cp02996c
ER  - 

@article{
author = "Ostojić, Bojana and Bunker, P. R. and Schwerdtfeger, Peter and Assadollahzadeh, B. and Jensen, Per",
year = "2011",
abstract = "The present study of MgOMg is a continuation of our theoretical work on Group 2 M2O hypermetallic oxides. Previous ab initio calculations have shown that MgOMg has a linear (1)Sigma(+)(g) ground electronic state and a very low lying first excited triplet electronic state that is also linear; the triplet state has (3)Sigma(+)(u) symmetry. No gas phase spectrum of this molecule has been assigned, and here we simulate the infrared absorption spectrum for both states. We calculate the three-dimensional potential energy surface, and the electric dipole moment surfaces, of each of the two states using a multireference configuration interaction (MRCISD) approach based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions with a cc-pCVQZ basis set. A variational MORBID calculation using our potential energy and dipole moment surfaces is performed to determine rovibrational term values and to simulate the infrared absorption spectrum of the two states. We also calculate the dipole polarizability of both states at their equilibrium geometry in order to assist in the interpretation of future beam deflection experiments. Finally, in order to assist in the analysis of the electronic spectrum, we calculate the vertical excitation energies, and electric dipole transition matrix elements, for six excited singlet states and five excited triplet states using the state-average full valence CASSCF-MRCISD/aug-cc-pCVQZ procedure.",
publisher = "Royal Soc Chemistry, Cambridge",
journal = "Physical Chemistry Chemical Physics",
title = "The predicted spectrum of the hypermetallic molecule MgOMg",
volume = "13",
number = "16",
pages = "7546-7553",
doi = "10.1039/c0cp02996c"
}

Ostojić, B., Bunker, P. R., Schwerdtfeger, P., Assadollahzadeh, B.,& Jensen, P.. (2011). The predicted spectrum of the hypermetallic molecule MgOMg. in Physical Chemistry Chemical Physics
Royal Soc Chemistry, Cambridge., 13(16), 7546-7553.
https://doi.org/10.1039/c0cp02996c

Ostojić B, Bunker PR, Schwerdtfeger P, Assadollahzadeh B, Jensen P. The predicted spectrum of the hypermetallic molecule MgOMg. in Physical Chemistry Chemical Physics. 2011;13(16):7546-7553.
doi:10.1039/c0cp02996c .

Ostojić, Bojana, Bunker, P. R., Schwerdtfeger, Peter, Assadollahzadeh, B., Jensen, Per, "The predicted spectrum of the hypermetallic molecule MgOMg" in Physical Chemistry Chemical Physics, 13, no. 16 (2011):7546-7553,
https://doi.org/10.1039/c0cp02996c . .

TY  - JOUR
AU  - Ostojić, Bojana
AU  - Jensen, Per
AU  - Schwerdtfeger, Peter
AU  - Assadollahzadeh, B.
AU  - Bunker, P. R.
PY  - 2010
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/711
AB  - Hypermetallation is a concept that applies to molecules having metal stoichiometries that exceed normal valence, and BeOBe is just one example of such a molecule. Previous ab initio calculations and spectroscopic studies have shown that BeOBe has a linear (1)Sigma(+)(g) ground electronic state and a very low lying (3)Sigma(+)(u) first excited electronic state. As the gas phase infrared spectrum of this molecule is unknown, we simulate such absorption spectra for both of these electronic states. To this end, we calculate the three-dimensional potential energy surfaces and the electric dipole moment surfaces of each of the two states using a multireference configuration interaction (MRCISD) approach based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions. This is followed by variational MORBID calculations, using our potential energy and dipole moment surfaces, in order to determine rovibrational term values and to simulate the infrared absorption spectrum of both the singlet and triplet states. We also calculate the dipole polarizability for both states at their equilibrium geometry, as this is of interest for probing the molecule in future beam deflection experiments.
PB  - Academic Press Inc Elsevier Science, San Diego
T2  - Journal of Molecular Spectroscopy
T1  - The predicted infrared spectrum of the hyperberyllium molecule BeOBe in its (X)over-tilde(1)Sigma(+)(g) and (a)over-tilde(3)Sigma(+)(u) electronic states
VL  - 263
IS  - 1
SP  - 21
EP  - 26
DO  - 10.1016/j.jms.2010.06.008
ER  - 

@article{
author = "Ostojić, Bojana and Jensen, Per and Schwerdtfeger, Peter and Assadollahzadeh, B. and Bunker, P. R.",
year = "2010",
abstract = "Hypermetallation is a concept that applies to molecules having metal stoichiometries that exceed normal valence, and BeOBe is just one example of such a molecule. Previous ab initio calculations and spectroscopic studies have shown that BeOBe has a linear (1)Sigma(+)(g) ground electronic state and a very low lying (3)Sigma(+)(u) first excited electronic state. As the gas phase infrared spectrum of this molecule is unknown, we simulate such absorption spectra for both of these electronic states. To this end, we calculate the three-dimensional potential energy surfaces and the electric dipole moment surfaces of each of the two states using a multireference configuration interaction (MRCISD) approach based on full-valence complete active space self-consistent field (FV-CASSCF) wavefunctions. This is followed by variational MORBID calculations, using our potential energy and dipole moment surfaces, in order to determine rovibrational term values and to simulate the infrared absorption spectrum of both the singlet and triplet states. We also calculate the dipole polarizability for both states at their equilibrium geometry, as this is of interest for probing the molecule in future beam deflection experiments.",
publisher = "Academic Press Inc Elsevier Science, San Diego",
journal = "Journal of Molecular Spectroscopy",
title = "The predicted infrared spectrum of the hyperberyllium molecule BeOBe in its (X)over-tilde(1)Sigma(+)(g) and (a)over-tilde(3)Sigma(+)(u) electronic states",
volume = "263",
number = "1",
pages = "21-26",
doi = "10.1016/j.jms.2010.06.008"
}

Ostojić, B., Jensen, P., Schwerdtfeger, P., Assadollahzadeh, B.,& Bunker, P. R.. (2010). The predicted infrared spectrum of the hyperberyllium molecule BeOBe in its (X)over-tilde(1)Sigma(+)(g) and (a)over-tilde(3)Sigma(+)(u) electronic states. in Journal of Molecular Spectroscopy
Academic Press Inc Elsevier Science, San Diego., 263(1), 21-26.
https://doi.org/10.1016/j.jms.2010.06.008

Ostojić B, Jensen P, Schwerdtfeger P, Assadollahzadeh B, Bunker PR. The predicted infrared spectrum of the hyperberyllium molecule BeOBe in its (X)over-tilde(1)Sigma(+)(g) and (a)over-tilde(3)Sigma(+)(u) electronic states. in Journal of Molecular Spectroscopy. 2010;263(1):21-26.
doi:10.1016/j.jms.2010.06.008 .

Ostojić, Bojana, Jensen, Per, Schwerdtfeger, Peter, Assadollahzadeh, B., Bunker, P. R., "The predicted infrared spectrum of the hyperberyllium molecule BeOBe in its (X)over-tilde(1)Sigma(+)(g) and (a)over-tilde(3)Sigma(+)(u) electronic states" in Journal of Molecular Spectroscopy, 263, no. 1 (2010):21-26,
https://doi.org/10.1016/j.jms.2010.06.008 . .