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SebWouters / CheMPS2

CheMPS2: a spin-adapted implementation of DMRG for ab initio quantum chemistry
GNU General Public License v2.0
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How to use CHEMPS2 with OpenMolcas? #61

Closed ghost closed 6 years ago

ghost commented 6 years ago

Dear Sebastian,

The CHEMPS2 interface is available in OpenMolcas. However, there is no instruction on how to use CHEMPS2 with OpenMolcas right now. Could you please suggest me some basic keywords to use this interface or how to obtain FCIDUMP file through this interface and then I can use CHEMPS2 as a standalone DMRG-CASPT2 implementation?

Thank you very much.

Hassenky

quanp commented 6 years ago

Hi,

First you should install both CheMPS2 and OpenMolcas with the interface. I wrote an instruction for this here: https://molcas.gitlab.io/doc/sphinx/installation.guide/dmrginst.html

There are two tests you can try DMRG-CASPT2 and learn the basis keywords: https://gitlab.com/Molcas/OpenMolcas/blob/master/test/grayzone/850.input https://gitlab.com/Molcas/OpenMolcas/blob/master/test/grayzone/851.input

If you are familiar with Molcas, then doing DMRG with Molcas is very similar, with some extra keywords in RASSCF and CASPT2 modules. https://molcas.gitlab.io/doc/sphinx/users.guide/programs/rasscf.html?highlight=dmrg https://molcas.gitlab.io/doc/sphinx/users.guide/programs/caspt2.html

The FCIDUMP file is always produced in each DMRG iteration so you can obtain it at any time. If you're doing large molecule with large basis set, I suggest not to use CheMPS2 as a standalone for DMRG-CASPT2. Use DMRG-CASPT2 in the Molcas interface instead.

Best regards, Quan

ghost commented 6 years ago

Thank you so much @quanp. I am reading your instruction. Hassenky