Molcas Forum

vkj

Member

Registered: 2019-04-10

Posts: 26

The SADREF keyword confusion

Dear developers,

I have confusions regarding keywords to use for analytic grad/NAC at caspt2.

1. I am not clear when to use the SADREF keyword for analytical gradients at CASPT2. Do I have always put it whether its SS-CASPT2 /(M,X,R)-multistate variants. I put the constraint that my underlying CASSCF/RASSCF is always state-averaged over multiple roots.

1. For the NAC computations, do I need just the NAC keyword and no SADREF/GRDT in all cases ?

EDITS to original question
Dear developers,

1. I have additional issues in using new analytical NAC. On the compiled master downloaded on 16 Feb 2023, the analytical NAC seems to only work inside the SLAPAF module. Outside it the program crashes complaining it can't do numerical NAC. On a related note, inside the SLAPAF module the program automagically switches to analytical grads without using SADREF/GRDT,   but in a single point computation these keywords are necessary to avoid NUMERICAL_GRADS.

2. In addition, in the ALASKA section, the  "Total derivative coupling" is identical to "CI derivative coupling". So, the division by energy-difference is not being performed. For same struct/basis-set the values are identical to what is obtained in BAGEL by using the "noweight" keyword which doesn't weigh the terms by energy-difference

VKJ

Last edited by vkj (2023-02-17 12:59:35)