Generation of potential energy curves for the X1Sigma(+)g, B1Delta(+)g, and B'1Sigma(+)g states of C2 using the effective valence shell Hamiltonian method

Rajat K Chaudhuri; Karl F Freed

doi:10.1063/1.1879812

Generation of potential energy curves for the X1Sigma(+)g, B1Delta(+)g, and B'1Sigma(+)g states of C2 using the effective valence shell Hamiltonian method

J Chem Phys. 2005 Apr 15;122(15):154310. doi: 10.1063/1.1879812.

Authors

Rajat K Chaudhuri¹, Karl F Freed

Affiliation

¹ Indian Institute of Astrophysics, Bangalore-560034, India. rkchaudh@kff1.uchicago.edu

PMID: 15945638
DOI: 10.1063/1.1879812

Abstract

Calculations of the ground and excited state potential energy curves of C2 using the third-order effective valence Hamiltonian (Hv3rd) method are benchmarked against full configuration interaction and other correlated single-reference perturbative and nonperturbative theories. The large nonparallelity errors (NPEs) exhibited even by state-of-art coupled cluster calculations through perturbative triples indicate a serious deficiency of these single-reference theories. The Hv method, on the other hand, produces a much reduced NPE, rendering it a viable approximate many-body method for accurately determining global ground and excited state potential energy curvessurfaces.