Re: [AMBER] Arsenic force field parametrization

From: Jason Swails <>
Date: Wed, 27 May 2015 11:47:08 -0400

On Wed, May 27, 2015 at 11:28 AM, Pengfei Li <>

> Hi Shilpa,
> I checked the ORCA program and found that it could generate Hessian matrix
> very easily, which can be used for the force constant calculation. But it
> could not perform Merz-Kollman charge calculation. There is a replacement
> for that which is called CHELPG charge calculation, but it is not easy to
> generate the charge points on the surface of molecule for the procedures
> are complicated, while these points are needed for the RESP charge fitting.
> So up to now ORCA can not be a totally replacement for Gaussian. I will
> still try to find free-charge replacement in the future.

‚Äč.E.D. tools supports GAMESS, Firefly, and Gaussian (the former two are
released free-of-charge, I think, though they are not open source AFAIK).

So those might be options.

All the best,

Jason M. Swails
Rutgers University
Postdoctoral Researcher
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Received on Wed May 27 2015 - 09:00:04 PDT
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