Molcas Forum

David

Member

Registered: 2017-05-16

Posts: 85

QM/MM system gradient

Dear developers,

According to the molcas manual, both energy and gradient computations are feasible in the ESPF module. So I wonder is there possible to calculate a QM/MM system gradient via ESPF. Thanks in advance!

Best Regards!

niko

Member

From: Marseille

Registered: 2015-11-08

Posts: 59

Website

Re: QM/MM system gradient

Dear developers,

According to the molcas manual, both energy and gradient computations are feasible in the ESPF module. So I wonder is there possible to calculate a QM/MM system gradient via ESPF. Thanks in advance!

Best Regards!

Hi David,
QM/MM gradients are definitively available. See the Tinker keywords in Gateway and ESPF modules. In case you have to use link atom(s), you probably need to use the LAMOrokuma keyword in ESPF. Also, rHidden is Slapaf helps the convergence of a geometry optimization.
Hope this helps,
Nicolas

David

Member

Registered: 2017-05-16

Posts: 85

Re: QM/MM system gradient

Hi nicolas,
Thank you for your reply! I prepare for a QM/MM nonadiabatic dynamics task, and it requires Molcas provides QM/MM gradient, NACs... However, molcas output file seems does not print QM/MM gradient automatically, therefore, can I print QM/MM gradient by employing some key words or other?
Best regards!

niko

Member

From: Marseille

Registered: 2015-11-08

Posts: 59

Website

Re: QM/MM system gradient

However, molcas output file seems does not print QM/MM gradient automatically, therefore, can I print QM/MM gradient by employing some key words or other?

Hi David,
1) You may increase the level of printing using the MOLCAS_PRINT env variable (see https://molcas.gitlab.io/OpenMolcas/sph … _emil.html)
2) Note that Molcas is not aware of all QM and MM atoms, unless you have included all of them in the QMMM part in Tinker key file. Accordingly, it may not print gradient contributions for some (most?) MM atoms.