I was wondering how can I get vertical gradient/verticah hessian models of PES using qchem. How should I be calculating hessian or gradient ?
Can you please clarify what you mean by a vertical model?
I mean vertical gradient or vertical hessian models of PES to calculate non radiative rates and emission spectra
I know what you mean and while you can compute the Hessian at any point you want, Q-Chem by itself does not calculate the relevant Franck-Condon factors. Those can be computed with the external ezFCF program, see here: