AMBER Archive (2007)

Subject: Re: AMBER: Employing SCC-DFTB with a periodic boundary condtion

From: Gustavo Seabra (gustavo.seabra_at_gmail.com)
Date: Thu Apr 26 2007 - 08:18:32 CDT

ÇÑÀç¹ü wrote:
> Dear all users.
>
> I was going to use SCC-DFTB for QM/MM simulation, but I wonder if I can use the method with a periodic boundary condition. The manual says SCC-DFTB implementation does not support Ewald summation, so I used qm_ewald=0 in the &qmmm namelist. However, if I use NTB=1 in the &cntrl namelist for a periodic boundary condition, PME is always on. Then, can my simulation work properly without any problems?
>
> Thanks
>
> Jaebeom.
Yes, it should work. Although PME over the *classical* atoms is on,
qm_pme will be off. You will not have Ewald or PME tratment for long
range electrostatics involving the QM atoms, so you may have to use a
large cutoff, but otherwise you should have no problems.

BTW, this issue has been solved for the next release (Amber 10).

Gustavo.
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