[Chimera-users] Help in protein minimization

Elaine Meng meng at cgl.ucsf.edu
Mon Aug 3 14:11:16 PDT 2020

Hi Aishah,
This is a very large structure.  Chimera's minimization is somewhat slow and does not use distance cutoffs so it is expected to scale poorly with the number of atoms (roughly N-squared where N is the number of atoms).  It is not surprising that it would take a very long time, especially if your computer's calculation speed is not high.

All I can say is to use zero steps of conjugate gradient minimization which is much slower than the steepest-descent  minimization.  Still, it may be very slow or even not possible to finish, and you may need to use a dedicated molecular mechanics/dynamics program (AMBER, GROMACS, etc.) instead of Chimera if you want faster performance.

I hope this helps,
Elaine C. Meng, Ph.D.                       
UCSF Chimera(X) team
Department of Pharmaceutical Chemistry
University of California, San Francisco

> On Aug 1, 2020, at 7:24 AM, Aishah Hisham <aishahhisham2b at yahoo.com> wrote:
> Hi, I'm doing protein minimization using Chimera 1.14
> However, I'm not sure if something was wrong with my structure or the software as it takes hours to run, the software is not responding and sometimes the structure went missing after running.
> Here I attached the protein needed to be minimized.
> I use the default setting with Gasteiger charges.
> Thank you.
> Best regards. 
> <AH env.pdb>

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