Re: How to get the right density of a methane system

From: Francesco Pietra (
Date: Sat Aug 12 2017 - 01:07:54 CDT

Hi Monika:
Have a look at

F. Pietra “On Dioxygen and Substrate Access to Soluble Methane
Monooxygenases. An all-Atom Molecular Dynamics Investigation in Water
Solution.” Chemistry&Biodiversity, *2016*, e1600158 DOI:

There you will find very good CHARMM parameters for methane, albeit not
tried for the liquid state

On Sat, Aug 12, 2017 at 4:56 AM, Monika Madhavi <>

> Dear all,
> I want to simulate a system of liquid methane at 91 K and 1 atm. I used
> some opls parameters from literature and converted them to CHARMM and used
> for my simulation. Initially I heated the system in NVT and then performed
> NPT. The system equillibriates but the density of methane after
> equillibration is higher than the experimental values. What could be the
> problem, the force field? or are there any special techniques to get the
> right density of a system. I am using NAMD with CHARMM for my simulations--94eb2c148b842a03a005568840c3--

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