Re: About changing charge/multiplicity during QM-MM

From: Gerard Rowe (
Date: Mon Apr 15 2019 - 08:06:52 CDT

Hi Francesco,

Yes, it is definitely possible. After converging to the BS solution, your NAMD input should specify the multiplicity of the BS state. As far as I'm aware, there is no explicit information in the GBW file that indicates the spin state for Orca to read in, so you always need to let it know what you want. One other note, you should make sure you specify UKS in your input line. Orca will default to a restricted (i.e., not an open-shell BS singlet) wavefunction if it sees a singlet value in the muliplicity line.


From: Francesco Pietra <>
Sent: Sunday, April 14, 2019 2:31 AM
To: Gerard Rowe; NAMD
Subject: Fwd: namd-l: About changing charge/multiplicity during QM-MM

A BS single point, for the last said system, with settings

! B3LYP def2-TZVP SlowConv
%scf MaxIter 10000

Flipspin 77
FinalMs 0

*xyz 0 11

converged HS in 55 SCF iterations, then carried out only 3 BS iterations (in the allowed 24hr).

On restarting with the same input command qmmm.job, the qmmm.gbw file was read, including MO. However, the simulation starts again with very slow HS SCF iterations, i.e., the allowed 24hr would be again too short for BS. From orca manual and web I was unable to find the way to have the simulation starting directly from BS. Is that at all possible?


---------- Forwarded message ---------
From: Francesco Pietra <<>>
Date: Fri, Apr 12, 2019 at 5:30 PM
Subject: Re: namd-l: About changing charge/multiplicity during QM-MM
To: Gerard Rowe <<>>
Cc:<> <<>>

Yes I noticed the problem, especially the ferromagnetic. Nonetheless I was happy that ice could be broken with B3LYP, although still inadequately. i had already attempted with " ! B3LYP def2-TZVP " but it proved much too slow--_000_DM6PR19MB29870E48636A6FDC345B14CFD12B0DM6PR19MB2987namp_--

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