From: David Ricardo Figueroa Blanco <dr.figueroa10.uniandes.edu.co>
Date: Thu, 24 Oct 2019 19:55:47 +0000


Thank you for your comment,

My molecule doesn't have CMap terms but when I used ParmEd as

gmx_top = pmd.load_file('topol.top',xyz='/confout.gro')
gmx_top.save('DAV.top', format='amber')
gmx_top.save('DAV.crd', format='rst7')

the FLAG_AMBER_ATOM_TYPE express and only reads atoms types with 4characters as Robin mention before. So there is any recommendation to solve this problem, maybe using gromber o creating charmm files and then use chamber ?

Thank you for your time and consideration.


From: Robin Betz <robin.robinbetz.com<mailto:robin.robinbetz.com?Subject=Re%3A%20%5BAMBER%5D%20PARAMFIT>>
Date: Mon, 23 Sep 2019 16:05:18 -0700

Hi David,

Paramfit will work with the CHARMM force field as long as your molecule
doesn't contain any CMAP terms. For small molecules, this shouldn't be an
issue and the energy calculation should come out the same. I've used
Paramfit without a problem for CHARMM files.
Be careful with atom names though-- CHARMM will have 6-character atom names
and AMBER/paramfit expects 4. If you create your prmtop with ParmEd's
chamber functionality this will be handled for you.


On Mon, Sep 23, 2019 at 8:28 AM David Ricardo Figueroa Blanco <
dr.figueroa10.uniandes.edu.co> wrote:

> Hi.
> I am trying to generate new force field parameters for two force fields
> (AMBER and CHARMM) but I would like to know if it is possible to perform
> the process with a topology file that contains CHARMM parameters with
> paramfit. Is it possible to change the function to evaluate energy, for
> example to CHARMM equation?
> Thank you for your time and consideration.
> Best Regards.
> David
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Received on Thu Oct 24 2019 - 13:00:02 PDT
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