Erratum: “Calculation of converged rovibrational energies and partition function for methane using vibrational–rotational configuration interaction” [J. Chem. Phys. 121, 2071 (2004)]

2011 ◽  
Vol 135 (11) ◽  
pp. 119904 ◽  
Author(s):  
Arindam Chakraborty ◽  
Donald G. Truhlar ◽  
Joel M. Bowman ◽  
Stuart Carter
Keyword(s):  
Partition Function ◽  
Configuration Interaction ◽  
Chem Phys ◽  
Rovibrational Energies

Erratum: Pseudospectral full configuration interaction [J. Chem. Phys. 97, 1876 (1992)]

1993 ◽  
Vol 99 (5) ◽  
pp. 4238-4238 ◽  
Author(s):  
Todd J. Martinez ◽  
Aseem Mehta ◽  
Emily A. Carter
Keyword(s):  
Configuration Interaction ◽  
Chem Phys ◽  
Full Configuration Interaction

scholarly journals Low-Cost Molecular Excited States from a State-Averaged Resonating Hartree-Fock Approach

2019 ◽  
Author(s):  
Jacob Nite ◽  
Carlos A. Jimenez-Hoyos
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Low Cost ◽  
Computational Cost ◽  
Mean Field ◽  
Chem Phys ◽  
Spin Projection ◽  
Excitation Energies ◽  
Hartree Fock ◽  
Orbital Relaxation

Quantum chemistry methods that describe excited states on the same footing as the ground state are generally scarce. In previous work, Gill et al. (J. Phys. Chem. A 112, 13164 (2008)) and later Sundstrom and Head-Gordon (J. Chem. Phys. 140, 114103 (2014)) considered excited states resulting from a non-orthogonal configuration interaction (NOCI) on stationary solutions of the Hartree–Fock equations. We build upon those contributions and present the state-averaged resonating Hartree–Fock (sa-ResHF) method, which differs from NOCI in that spin-projection and orbital relaxation effects are incorporated from the onset. Our results in a set of small molecules (alanine, formaldehyde, acetaldehyde, acetone, formamide, and ethylene) suggest that sa-ResHF excitation energies are a notable improvement over configuration interaction singles (CIS), at a mean-field computational cost. The orbital relaxation in sa-ResHF, in the presence of a spin-projection operator, generally results in excitation energies that are closer to the experimental values than the corresponding NOCI ones.

scholarly journals Low-Cost Molecular Excited States from a State-Averaged Resonating Hartree-Fock Approach

2019 ◽  
Author(s):  
Jacob Nite ◽  
Carlos A. Jimenez-Hoyos
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Low Cost ◽  
Computational Cost ◽  
Mean Field ◽  
Chem Phys ◽  
Spin Projection ◽  
Excitation Energies ◽  
Hartree Fock ◽  
Orbital Relaxation

Quantum chemistry methods that describe excited states on the same footing as the ground state are generally scarce. In previous work, Gill et al. (J. Phys. Chem. A 112, 13164 (2008)) and later Sundstrom and Head-Gordon (J. Chem. Phys. 140, 114103 (2014)) considered excited states resulting from a non-orthogonal configuration interaction (NOCI) on stationary solutions of the Hartree–Fock equations. We build upon those contributions and present the state-averaged resonating Hartree–Fock (sa-ResHF) method, which differs from NOCI in that spin-projection and orbital relaxation effects are incorporated from the onset. Our results in a set of small molecules (alanine, formaldehyde, acetaldehyde, acetone, formamide, and ethylene) suggest that sa-ResHF excitation energies are a notable improvement over configuration interaction singles (CIS), at a mean-field computational cost. The orbital relaxation in sa-ResHF, in the presence of a spin-projection operator, generally results in excitation energies that are closer to the experimental values than the corresponding NOCI ones.

scholarly journals Hylleraas-Configuration Interaction (Hy-CI) Non-Relativistic Energies for the 3 1S, 4 1S, 5 1S, 6 1S, and 7 1S Excited States of the Beryllium Atom

2020 ◽  
Vol 125 ◽  
Author(s):  
James S. Sims
Keyword(s):  
Excited States ◽  
Configuration Interaction ◽  
Ground States ◽  
Chem Phys ◽  
Isoelectronic Sequence ◽  
Variational Calculations

In a previous work Sims and Hagstrom [J Chem Phys 140,224312(2014)] reported Hylleraas-configuration interaction (Hy-CI) method variational calculations for the 1S ground states of the beryllium isoelectronic sequence with an estimated accuracy of 10 to 20 nanohartrees (nHa). In this work the calculations have been extended to the five higher states of the neutral beryllium atom, 3 1S, 4 1S, 5 1S, 6 1S, and 7 1S. The best non-relativistic energies obtained for these states are -14.4182 4034 6, -14.3700 8789 0, -14.3515 1167 6, -14.3424 0357 8, and -14.3372 6649 96 Ha, respectively. The 6 1S result is superior to the known reference energy for that state, while for the 7 1S state there is no other comparable calculation.

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