Hi Catherine,
Only closed-shell calculations are possible with the QM implementations in Amber (DFTB or semiempirical). Open-shell calculations are only possible with external QM programs.
All the best,
Andy
—
Dr. Andreas W. Goetz
Assistant Project Scientist
San Diego Supercomputer Center
Tel: +1-858-822-4771
Email: agoetz.sdsc.edu
Web: www.awgoetz.de
> On Aug 17, 2016, at 3:22 PM, Corum, Katharine W <katharine-corum.uiowa.edu> wrote:
>
> Hi Everyone,
>
>
> I am doing a QM/MM calculation using Amber16 and the QM region has an odd number of electrons. And my output tells me so...
>
>
> --------------------------------------------------------------------------------
> 3.1 QM CALCULATION INFO
> --------------------------------------------------------------------------------
> QMMM: System specified with odd number of electrons ( 85)
> QMMM: but odd spin ( 1). You most likely have the charge of
> QMMM: QM region (qmcharge) set incorrectly. Correct error and re-run calculation.
>
>
> I have set the qmcharge to equal -2 since the QM region has a -2 charge so I know my qmcharge value is correct. I tried to change the spin from 1 to 2 and received this error message.
>
>
> PARAMETER RANGE CHECKING:
> parameter QMMM: (Spin multiplicity) has value 2
> This is outside the legal range
> Lower limit: 1 Upper limit: 1
> The limits may be adjustable; search in the .h files
>
> My questions are:
> 1. Can I run a QM/MM job with an odd number of electrons?
> 2. What is the .h file the job is referring to?
>
> I see that this question has come up a couple times in the archive, but I did not see a question regarding this issue and the current version.
>
> Thank you very much!
> Katie
>
>
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Received on Wed Aug 17 2016 - 17:00:02 PDT
