On the evaluation of analytic energy derivatives for correlated wave functions
Abstract
It is shown that to obtain the (2n)th and (2n+1)th energy gradients, it is only necessary to solve equations of the difficulty of the nth order coupled perturbed equations for the orbital and configuration interaction (CI) parameters. For example, to find analytic second and third energy derivatives for CI wave functions, it is only necessary to solve the first order coupled perturbed equations and some related equations, for the effects of orbital rotations. Similar results apply for gradients of energies derived using perturbation theory.
 Publication:

Journal of Chemical Physics
 Pub Date:
 December 1984
 DOI:
 10.1063/1.447489
 Bibcode:
 1984JChPh..81.5031H