Performance of multireference and equation-of-motion coupled-cluster methods for potential energy surfaces of low-lying excited states: symmetric and asymmetric dissociation of water

The Journal of Chemical Physics
Xiangzhu Li, Josef Paldus

Abstract

Multireference (MR), general-model-space (GMS), state-universal (SU) coupled-cluster (CC) method that considers singly (S) and doubly (D) excited cluster amplitudes relative to the reference configurations spanning the model space (GMS SU CCSD), as well as its externally corrected (ec) version (N,M)-CCSD that employs N-reference MR CISD as an external source of higher-than-pair cluster amplitudes in a M-reference GMS CCSD, are employed to investigate low-lying states of the water molecule. The emphasis is on a generation of several low lying states belonging to the same symmetry species. Cuts of the potential energy surface (PES) corresponding to the breaking of a single OH bond and leading to the OH+H fragments, as well as the simultaneous breaking of both bonds into the O+2H are considered. Relying on a simple ab initio model that enables a comparison with the exact full configuration interaction energies, the performance of the GMS-based methods is assessed in the whole relevant range of internuclear separations. It is shown that the ec (N,M)-CCSD version provides best results for both the singlet and the triplet states considered. The same cuts of the PES are then explored using a realistic aug-cc-pVTZ basis set. For triple...Continue Reading

References

Jul 23, 2004·The Journal of Chemical Physics·Xiangzhu Li, Josef Paldus
Dec 27, 2005·The Journal of Chemical Physics·Piotr Piecuch, Marta Włoch
May 13, 2006·The Journal of Chemical Physics·Xiangzhu Li, Josef Paldus
Oct 25, 2006·The Journal of Chemical Physics·Francesco A EvangelistaHenry F Schaefer
Sep 4, 2007·The Journal of Chemical Physics·Jonathan J DorandoGarnet Kin-Lic Chan
Feb 6, 2008·The Journal of Chemical Physics·Andrew G Taube, Rodney J Bartlett
Feb 6, 2008·The Journal of Chemical Physics·Andrew G Taube, Rodney J Bartlett
Aug 14, 2008·The Journal of Chemical Physics·Xiangzhu Li, Josef Paldus
Feb 17, 2010·The Journal of Physical Chemistry. a·Xiangzhu Li, Josef Paldus

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Citations

Mar 25, 2010·The Journal of Chemical Physics·Xiangzhu Li, Josef Paldus
Jun 15, 2011·The Journal of Chemical Physics·Xiangzhu Li, Josef Paldus
Jan 10, 2012·Chemical Reviews·Dmitry I LyakhRodney J Bartlett

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Methods Mentioned

BETA
RMR

Software Mentioned

SU
EOM
GAMESS
4R
CCSD
RMR
SR

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