TY  - JOUR
AU  - Stepanović, Stepan
AU  - Lai, Rui
AU  - Elstner, Marcus
AU  - Gruden, Maja
AU  - Garcia-Fernandez, Pablo
AU  - Cui, Qiang
PY  - 2020
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4030
AB  - To improve the description of interactions among the localized d, f electrons in transition metals, we have introduced a ligand-field motivated contribution into the Density Functional Tight Binding (DFTB) model. Referred to as DFTB3+U, the approach treats the d, f electron repulsions with rotationally invariant orbital–orbital interactions and a Hartree–Fock model; this represents a major conceptual improvement over the original DFTB3 approach, which treats the d, f-shell interactions in a highly averaged fashion without orbital level of description. The DFTB3+U approach is tested using a series of nickel compounds that feature Ni(II) and Ni(III) oxidation states. By using parameters developed with the original DFTB3 Hamiltonian and empirical +U parameters (F0/2/4 Slater integrals), we observe that the DFTB3+U model indeed provides substantial improvements over the original DFTB3 model for a number of properties of the nickel compounds, including the population and spin polarization of the d-shell, nature of the frontier orbitals, ligand field splitting and the energy different between low and high spin states at OPBE optimized structures. This proof-of-concept study suggests that with self-consistent parameterization of the electronic and +U parameters, the DFTB3+U model can develop into a promising model that can be used to efficiently study reactive events involving transition metals ion condensed phase systems. The methodology can be integrated with other approximate QM methods as well, such as the extended tight binding (xTB) approach.
PB  - Royal Society of Chemistry (RSC)
T2  - Physical Chemistry Chemical Physics
T1  - Improvement of d–d interactions in density functional tight binding for transition metal ions with a ligand field model: assessment of a DFTB3+                    U                    model on nickel coordination compounds
VL  - 22
IS  - 46
SP  - 27084
EP  - 27095
DO  - 10.1039/D0CP04694A
ER  - 

@article{
author = "Stepanović, Stepan and Lai, Rui and Elstner, Marcus and Gruden, Maja and Garcia-Fernandez, Pablo and Cui, Qiang",
year = "2020",
abstract = "To improve the description of interactions among the localized d, f electrons in transition metals, we have introduced a ligand-field motivated contribution into the Density Functional Tight Binding (DFTB) model. Referred to as DFTB3+U, the approach treats the d, f electron repulsions with rotationally invariant orbital–orbital interactions and a Hartree–Fock model; this represents a major conceptual improvement over the original DFTB3 approach, which treats the d, f-shell interactions in a highly averaged fashion without orbital level of description. The DFTB3+U approach is tested using a series of nickel compounds that feature Ni(II) and Ni(III) oxidation states. By using parameters developed with the original DFTB3 Hamiltonian and empirical +U parameters (F0/2/4 Slater integrals), we observe that the DFTB3+U model indeed provides substantial improvements over the original DFTB3 model for a number of properties of the nickel compounds, including the population and spin polarization of the d-shell, nature of the frontier orbitals, ligand field splitting and the energy different between low and high spin states at OPBE optimized structures. This proof-of-concept study suggests that with self-consistent parameterization of the electronic and +U parameters, the DFTB3+U model can develop into a promising model that can be used to efficiently study reactive events involving transition metals ion condensed phase systems. The methodology can be integrated with other approximate QM methods as well, such as the extended tight binding (xTB) approach.",
publisher = "Royal Society of Chemistry (RSC)",
journal = "Physical Chemistry Chemical Physics",
title = "Improvement of d–d interactions in density functional tight binding for transition metal ions with a ligand field model: assessment of a DFTB3+                    U                    model on nickel coordination compounds",
volume = "22",
number = "46",
pages = "27084-27095",
doi = "10.1039/D0CP04694A"
}

Stepanović, S., Lai, R., Elstner, M., Gruden, M., Garcia-Fernandez, P.,& Cui, Q.. (2020). Improvement of d–d interactions in density functional tight binding for transition metal ions with a ligand field model: assessment of a DFTB3+                    U                    model on nickel coordination compounds. in Physical Chemistry Chemical Physics
Royal Society of Chemistry (RSC)., 22(46), 27084-27095.
https://doi.org/10.1039/D0CP04694A

Stepanović S, Lai R, Elstner M, Gruden M, Garcia-Fernandez P, Cui Q. Improvement of d–d interactions in density functional tight binding for transition metal ions with a ligand field model: assessment of a DFTB3+                    U                    model on nickel coordination compounds. in Physical Chemistry Chemical Physics. 2020;22(46):27084-27095.
doi:10.1039/D0CP04694A .

Stepanović, Stepan, Lai, Rui, Elstner, Marcus, Gruden, Maja, Garcia-Fernandez, Pablo, Cui, Qiang, "Improvement of d–d interactions in density functional tight binding for transition metal ions with a ligand field model: assessment of a DFTB3+                    U                    model on nickel coordination compounds" in Physical Chemistry Chemical Physics, 22, no. 46 (2020):27084-27095,
https://doi.org/10.1039/D0CP04694A . .

TY  - JOUR
AU  - Gruden, Maja
AU  - Anđelković, Ljubica
AU  - Jissy, Akkarapattiakal Kuriappan
AU  - Stepanović, Stepan
AU  - Zlatar, Matija
AU  - Cui, Qiang
AU  - Elstner, Marcus
PY  - 2017
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2734
AB  - Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory.
PB  - Wiley, Hoboken
T2  - Journal of Computational Chemistry
T1  - Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules
VL  - 38
IS  - 25
SP  - 2171
EP  - 2185
DO  - 10.1002/jcc.24866
ER  - 

@article{
author = "Gruden, Maja and Anđelković, Ljubica and Jissy, Akkarapattiakal Kuriappan and Stepanović, Stepan and Zlatar, Matija and Cui, Qiang and Elstner, Marcus",
year = "2017",
abstract = "Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory.",
publisher = "Wiley, Hoboken",
journal = "Journal of Computational Chemistry",
title = "Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules",
volume = "38",
number = "25",
pages = "2171-2185",
doi = "10.1002/jcc.24866"
}

Gruden, M., Anđelković, L., Jissy, A. K., Stepanović, S., Zlatar, M., Cui, Q.,& Elstner, M.. (2017). Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules. in Journal of Computational Chemistry
Wiley, Hoboken., 38(25), 2171-2185.
https://doi.org/10.1002/jcc.24866

Gruden M, Anđelković L, Jissy AK, Stepanović S, Zlatar M, Cui Q, Elstner M. Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules. in Journal of Computational Chemistry. 2017;38(25):2171-2185.
doi:10.1002/jcc.24866 .

Gruden, Maja, Anđelković, Ljubica, Jissy, Akkarapattiakal Kuriappan, Stepanović, Stepan, Zlatar, Matija, Cui, Qiang, Elstner, Marcus, "Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules" in Journal of Computational Chemistry, 38, no. 25 (2017):2171-2185,
https://doi.org/10.1002/jcc.24866 . .

TY  - JOUR
AU  - Gruden, Maja
AU  - Anđelković, Ljubica
AU  - Jissy, Akkarapattiakal Kuriappan
AU  - Stepanović, Stepan
AU  - Zlatar, Matija
AU  - Cui, Qiang
AU  - Elstner, Marcus
PY  - 2017
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2131
AB  - Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory.
PB  - Wiley, Hoboken
T2  - Journal of Computational Chemistry
T1  - Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules
VL  - 38
IS  - 25
SP  - 2171
EP  - 2185
DO  - 10.1002/jcc.24866
ER  - 

@article{
author = "Gruden, Maja and Anđelković, Ljubica and Jissy, Akkarapattiakal Kuriappan and Stepanović, Stepan and Zlatar, Matija and Cui, Qiang and Elstner, Marcus",
year = "2017",
abstract = "Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory.",
publisher = "Wiley, Hoboken",
journal = "Journal of Computational Chemistry",
title = "Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules",
volume = "38",
number = "25",
pages = "2171-2185",
doi = "10.1002/jcc.24866"
}

Gruden, M., Anđelković, L., Jissy, A. K., Stepanović, S., Zlatar, M., Cui, Q.,& Elstner, M.. (2017). Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules. in Journal of Computational Chemistry
Wiley, Hoboken., 38(25), 2171-2185.
https://doi.org/10.1002/jcc.24866

Gruden M, Anđelković L, Jissy AK, Stepanović S, Zlatar M, Cui Q, Elstner M. Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules. in Journal of Computational Chemistry. 2017;38(25):2171-2185.
doi:10.1002/jcc.24866 .

Gruden, Maja, Anđelković, Ljubica, Jissy, Akkarapattiakal Kuriappan, Stepanović, Stepan, Zlatar, Matija, Cui, Qiang, Elstner, Marcus, "Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules" in Journal of Computational Chemistry, 38, no. 25 (2017):2171-2185,
https://doi.org/10.1002/jcc.24866 . .