[AMBER] QM region has an odd number of electrons

From: Corum, Katharine W <katharine-corum.uiowa.edu>
Date: Wed, 17 Aug 2016 21:22:53 +0000

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...

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 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!

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Received on Wed Aug 17 2016 - 14:30:02 PDT
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