Self-consistent implementation of a nonlocal van der Waals density functional with a Gaussian basis set

2008 ◽  
Vol 129 (1) ◽  
pp. 014106 ◽  
Author(s):  
Oleg A. Vydrov ◽  
Qin Wu ◽  
Troy Van Voorhis
Keyword(s):  
Density Functional ◽  
Van Der Waals ◽  
Basis Set ◽  
Self Consistent ◽  
Gaussian Basis Set

scholarly journals Study of odd–even effects in physisorption and chemisorption of Ar, N2, O2 and NO on open shell Ag11–13+ clusters by means of self-consistent van der Waals density functional calculations

2019 ◽  
Vol 21 (45) ◽  
pp. 25158-25174
Author(s):  
Eva M. Fernández ◽  
Luis C. Balbás
Keyword(s):  
Small Molecules ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Van Der Waals ◽  
Open Shell ◽  
Self Consistent

Electronic and structural odd-even effects in the adsorption of small molecules on open shell silver cationic clusters have been rationalized.

Universal Gaussian basis functions in relativistic quantum chemistry: atomic Dirac–Fock–Coulomb and Dirac–Fock–Breit calculations

1992 ◽  
Vol 70 (6) ◽  
pp. 1822-1826 ◽  
Author(s):  
G. L. Malli ◽  
A. B. F. Da Silva ◽  
Yasuyuki Ishikawa
Keyword(s):  
Relativistic Quantum ◽  
Basis Set ◽  
Basis Sets ◽  
Interaction Energies ◽  
Gaussian Basis Sets ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Gaussian Basis Set ◽  
Good Agreement

Matrix Dirac–Fock–Coulomb and Dirac–Fock–Breit self-consistent field calculations are performed for a number of neutral atoms. He (Z = 2) through Xe (Z = 54), using the universal Gaussian basis set (18s, 12p, 11d) reported recently by Da Silva etal. The total Dirac–Fock–Coulomb, the Dirac–Fock–Breit, and the Breit interaction energies calculated with this universal Gaussian basis set are in good agreement with the corresponding values obtained by using an extensive well-tempered Gaussian basis set for the He through Ca (Z = 20) atoms. Although this universal Gaussian basis set is inadequate for the calculation of total Dirac–Fock–Coulomb and Dirac–Fock–Breit energies for the Kr, Sr, and Xe atoms, the Breit interaction energies calculated with this basis for these three atoms are in very good agreement with the corresponding Breit interaction energies obtained by using the extensive well-tempered Gaussian basis sets. Work is in progress to generate a more extensive and energetically better universal Gaussian basis set for He through Xe for its use in non-relativistic Hartree–Fock as well as Dirac–Fock self-consistent field calculations on polyatomics involving heavy atoms.

scholarly journals Achieving performance portability in Gaussian basis set density functional theory on accelerator based architectures in NWChemEx

2021 ◽  
pp. 102829
Author(s):  
David B. Williams-Young ◽  
Abhishek Bagusetty ◽  
Wibe A. de Jong ◽  
Douglas Doerfler ◽  
Hubertus J.J. van Dam ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Basis Set ◽  
Functional Theory ◽  
Performance Portability ◽  
Gaussian Basis Set

scholarly journals Theoretical Atomic Radii of Elements (H-Cm): A Non-Relativistic Study with Gaussian Basis Set Using HF, Post-HF and DFT Methods

2021 ◽  
Author(s):  
Krishnamohan Prasanna ◽  
Sooraj Sunil ◽  
Ajith Kumar ◽  
Jamesh Joseph
Keyword(s):  
Electron Correlation ◽  
Van Der Waals ◽  
Basis Set ◽  
Dft Methods ◽  
Ionization Energies ◽  
Spin Polarized ◽  
Gaussian Basis Set ◽  
Van Der Waals Radii ◽  
Atomic Radii ◽  
Good Agreement

<div><p>We calculated the most probable radius of an atom for elements from H to Cm. The calculations were carried out by using non-relativistic, spin polarized, HF, MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated with the experimental first ionization energies. This non-relativistic atomic radii were also compared with other theoretical atomic radii. With respect to the Dirac-Slater data, our values were in good agreement with the elements up to Sn. Relationship with van der Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div>

scholarly journals Theoretical Atomic Radii of Elements (H-Cm): A Non-Relativistic Study with Gaussian Basis Set Using HF, Post-HF and DFT Methods

2021 ◽  
Author(s):  
Krishnamohan Prasanna ◽  
Sooraj Sunil ◽  
Ajith Kumar ◽  
Jamesh Joseph
Keyword(s):  
Electron Correlation ◽  
Van Der Waals ◽  
Basis Set ◽  
Dft Methods ◽  
Ionization Energies ◽  
Spin Polarized ◽  
Gaussian Basis Set ◽  
Van Der Waals Radii ◽  
Atomic Radii ◽  
Good Agreement

<div><p>We calculated the most probable radius of an atom for elements from H to Cm. The calculations were carried out by using non-relativistic, spin polarized, HF, MP2 and DFT methods with all electron Gaussian basis set<i>. </i>Periodicity of atomic radii was correlated with the experimental first ionization energies. This non-relativistic atomic radii were also compared with other theoretical atomic radii. With respect to the Dirac-Slater data, our values were in good agreement with the elements up to Sn. Relationship with van der Waals radii of noble gases was discussed. Anomalous properties of Gd and Pd were examined. Linearity of lanthanide contraction of elements with <i>4f </i>electrons is illustrated. This linearity is found independent of the extent of electron correlation. S.I. give data of calculated radii and other correlated studies (with ionization energies, another theoretical radii etc.)</p></div>

scholarly journals Van der Waals density functional: Self-consistent potential and the nature of the van der Waals bond

2007 ◽  
Vol 76 (12) ◽  
Author(s):  
T. Thonhauser ◽  
Valentino R. Cooper ◽  
Shen Li ◽  
Aaron Puzder ◽  
Per Hyldgaard ◽  
...  
Keyword(s):  
Density Functional ◽  
Van Der Waals ◽  
Self Consistent ◽  
Van Der Waals Bond

scholarly journals Electronic Properties of Molecules and Surfaces with a Self-Consistent Interatomic van der Waals Density Functional

2015 ◽  
Vol 114 (17) ◽  
Author(s):  
Nicola Ferri ◽  
Robert A. DiStasio ◽  
Alberto Ambrosetti ◽  
Roberto Car ◽  
Alexandre Tkatchenko
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Van Der Waals ◽  
Self Consistent

A Robust Non-Self-Consistent Tight-Binding Quantum Chemistry Method for large Molecules

2019 ◽  
Author(s):  
Philipp Pracht ◽  
Eike Caldeweyher ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Computational Cost ◽  
Vibrational Frequencies ◽  
Molecular Structures ◽  
New Method ◽  
Basis Set ◽  
Semiempirical Methods ◽  
Electronic Interaction ◽  
Self Consistent

We propose a semiempirical quantum chemical method, designed for the fast calculation of molecular Geometries, vibrational Frequencies and Non-covalent interaction energies (GFN) of systems with up to a few thousand atoms. Like its predecessors GFN-xTB and GFN2-xTB, the new method termed GFN0-xTB is parameterized for all elements up to radon (Z = 86) and mostly shares well-known density functional tight-binding approximations as well as basis set and integral approximations. The main new feature is the avoidance of the self-consistent charge iterations leading to speed-ups of a factor of 2-20 depending on the size and electronic complexity of the system. This is achieved by including only quantum mechanical contributions up to first-order which are incorporated similar to the previous versions without any pair-specific parameterization. The essential electrostatic electronic interaction is treated by a classical electronegativity equilibration charge model yielding atomic partial charges that enter the electronic Hamiltonian indirectly. Furthermore, the atomic charge-dependent D4 dispersion correction is included to account for long range London correlation effects. Formulas for analytical total energy gradients with respect to nuclear displacements are derived and implemented in the <i>xtb </i>code allowing numerically very precise structure optimizations. The neglect of self-consistent energy terms not only leads to a large gain in computational speed but also can increase robustness in electronically difficult situations because ill-convergence or artificial charge-transfer (CT) is avoided. The comparison of GFN0-xTB and GFN/GFN2-xTB allows dissection of quantum electronic polarization and CT effects thereby improving our understanding of chemical bonding. Compared to the most sophisticated multipole-based GFN2-xTB model (which approaches DFT accuracy for the target properties closely), GFN0-xTB performs slightly worse for non-covalent interactions and molecular structures, while very good results are observed for conformational energies. Vibrational frequencies are obtained less accurately than with GFN/GFN2-xTB but they may still be useful for various purposes like estimating relative thermostatistical reaction energies. Most exceptional is the fact that even relatively complicated transition metal complex structures can be accurately optimized with a non-self-consistent quantum approach. The new method bridges the gap between force-fields and traditional semiempirical methods with its excellent computational cost to accuracy ratio and is intended to explore the chemical space of large molecular systems and solids.<br>

A Robust Non-Self-Consistent Tight-Binding Quantum Chemistry Method for large Molecules

2019 ◽  
Author(s):  
Philipp Pracht ◽  
Eike Caldeweyher ◽  
Sebastian Ehlert ◽  
Stefan Grimme
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Computational Cost ◽  
Vibrational Frequencies ◽  
Molecular Structures ◽  
New Method ◽  
Basis Set ◽  
Semiempirical Methods ◽  
Electronic Interaction ◽  
Self Consistent

We propose a semiempirical quantum chemical method, designed for the fast calculation of molecular Geometries, vibrational Frequencies and Non-covalent interaction energies (GFN) of systems with up to a few thousand atoms. Like its predecessors GFN-xTB and GFN2-xTB, the new method termed GFN0-xTB is parameterized for all elements up to radon (Z = 86) and mostly shares well-known density functional tight-binding approximations as well as basis set and integral approximations. The main new feature is the avoidance of the self-consistent charge iterations leading to speed-ups of a factor of 2-20 depending on the size and electronic complexity of the system. This is achieved by including only quantum mechanical contributions up to first-order which are incorporated similar to the previous versions without any pair-specific parameterization. The essential electrostatic electronic interaction is treated by a classical electronegativity equilibration charge model yielding atomic partial charges that enter the electronic Hamiltonian indirectly. Furthermore, the atomic charge-dependent D4 dispersion correction is included to account for long range London correlation effects. Formulas for analytical total energy gradients with respect to nuclear displacements are derived and implemented in the <i>xtb </i>code allowing numerically very precise structure optimizations. The neglect of self-consistent energy terms not only leads to a large gain in computational speed but also can increase robustness in electronically difficult situations because ill-convergence or artificial charge-transfer (CT) is avoided. The comparison of GFN0-xTB and GFN/GFN2-xTB allows dissection of quantum electronic polarization and CT effects thereby improving our understanding of chemical bonding. Compared to the most sophisticated multipole-based GFN2-xTB model (which approaches DFT accuracy for the target properties closely), GFN0-xTB performs slightly worse for non-covalent interactions and molecular structures, while very good results are observed for conformational energies. Vibrational frequencies are obtained less accurately than with GFN/GFN2-xTB but they may still be useful for various purposes like estimating relative thermostatistical reaction energies. Most exceptional is the fact that even relatively complicated transition metal complex structures can be accurately optimized with a non-self-consistent quantum approach. The new method bridges the gap between force-fields and traditional semiempirical methods with its excellent computational cost to accuracy ratio and is intended to explore the chemical space of large molecular systems and solids.<br>

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