Molcas Forum
Support and discussions for Molcas and OpenMolcas users and developers
You are not logged in.
- Topics: Active | Unanswered
Announcement
Please note: The forum's URL has changed. The new URL is: https://molcasforum.univie.ac.at. Please update your bookmarks!
You can choose an avatar and change the default style by going to "Profile" → "Personality" or "Display".#1 2019-08-09 10:56:41
- vkj
- Member
- Registered: 2019-04-10
- Posts: 29
Rasscf(RAS1,RAS3) tight energy convergence
Hi all,
I am having issues with achieving tight energy convergence(~1.0E-8) using only RAS1 and RAS3 spaces. I require a tight convergence for dynamics simulations. Using a CASSCF space(RAS1=0,RAS2=m+n,RAS3=0), such convergence is easily achieved but the time taken is too much (with added CASPT2). I hoped to achieve reasonable times with a (RAS1=m,RAS2=0,RAS3=n) space, but i cannot achieve convergence in RASSCF.
I am trying to play with SDAV /NOQUNE/levshft but i can achieve till 1.0E-7. Can anyone give some tips/tricks(?) to help achieve convergence within CIMX=200
Last edited by vkj (2019-08-09 11:05:58)
Offline
#2 2019-10-17 09:20:53
- nikolay
- Member
- From: Stuttgart
- Registered: 2016-03-21
- Posts: 54
Re: Rasscf(RAS1,RAS3) tight energy convergence
It is well known that RASSCF convergence is worse compare to CASSCF. It can be that you can't get reasonable WF with RAS. Maybe you need to keep some electrons in RAS2?
If there is a good reason to believe that the choice of RAS is good, you can try to converge CASSCF first and then do RASSCF on top of the converged orbitals.
Offline