coarse grain density not match with all-atom

[Pragati Sharma]

Dear all,

I have obtained coarse grained potentials for polybutadiene using IBI and run a simulation. All my coarse grained potentials matched the target distribution within '0.01' limit.

However after a coarse grained NPT run, my CG polymer density is very less.

all atom density: 850 kg/m^3 and CG density=540 kg/m^3.

I have used pressure corrections during IBI potential calculation.

Any idea on how to get desired polymer density.

I have heard of ramp correction. What is it. Would it help and any example on how it is set up.

Thanks,

Pragati

[Christoph Junghans]

On Fri, Dec 4, 2020 at 8:50 AM Pragati Sharma <praga...@gmail.com> wrote:
>
> Dear all,
>
> I have obtained coarse grained potentials for polybutadiene using IBI and run a simulation. All my coarse grained potentials matched the target distribution within '0.01' limit.
> However after a coarse grained NPT run, my CG polymer density is very less.
> all atom density: 850 kg/m^3 and CG density=540 kg/m^3.
>
> I have used pressure corrections during IBI potential calculation.
> Any idea on how to get desired polymer density.

Sorry, this is not my field of expertise, but maybe somebody else on
the mailing list knows.

>
> I have heard of ramp correction. What is it. Would it help and any example on how it is set up.

The simple and wjk pressure corrections implemented in VOTCA are both
ramp corrections.

Christoph

>
> Thanks,
> Pragati
>
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--
Christoph Junghans
Web: http://www.compphys.de