Re: changing value of coulomb constant

From: Brian Radak (
Date: Sun Apr 14 2019 - 11:47:16 CDT

Unfortunately this is not commonly done and requires a bit of an expert
touch. All internal evaluations in NAMD use the precompiler definition
COLOUMB inside src/common.h. You will have to change this value and

Note that you might still have a little bit of trouble depending on your
force field and input file format. The AMBER file format (and the extended
format for the CHARMM force field) implicitly uses its own value of COULOMB
(actually, the sqrt of it). A similar thing happens for the CHARMM Drude
force field in PSF format.


On Sun, Apr 14, 2019, 2:28 AM Akshay Prabhakant <>

> Hello everyone,
> I am dong a comparison study for a protein system using AMBER-MD and NAMD,
> using amber parameters, and for that I need to change the value of NAMD
> coulomb constant. How can I change the value of the coulomb constant if I
> have downloaded the NAMD_Linux-x86_64-multicore ?

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