AMBER Archive (2008)

Subject: RE: AMBER: QM/MM and unpaired spin

From: Ross Walker (
Date: Tue Dec 02 2008 - 21:42:37 CST

Hi Gustavo,

> **In principle**, SCC-DFTB can deal with the restricted open-shell
> case. But it hasn't been tested much, so you need to be careful.

I think this will need some hacking of the code though. As it stands right
now the value of spin from the mdin file does not appear to be used anywhere
inside the DFTB code so I can't see how one would actually select the spin.
Unless DFTB simply detects if there are an odd number of electrons and
selects a doublet. This of course prohibits things like triplets etc.

All the best

|\oss Walker

| Assistant Research Professor |
| San Diego Supercomputer Center |
| Tel: +1 858 822 0854 | EMail:- |
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