Posted by lydia on December 21, 2009 at 17:21:50:
In Reply to: Re: How to evaluate the one and two electrons integrals when the nucleus coordinates are changed but electron wavefunction are not changed? posted by Roland Lindh on December 19, 2009 at 12:14:32:
Thanks Roland very much for the reply.
I want to calculate the primary force constant K0, which is the second derivative of H with respect to small nuclear displacements Q at Q=0, and with the same wavefunction as that at Q=0, i.e., <ƒµ0„ H''(Q)„ ƒµ0>
(1)The overlap matrix does not change.
(2)The CASSCF OR MRCI wave funcion is better.