AMOEBA FF for NPT, NVT

[Daniel Konstantinovsky]

Hi everyone,

I'm very interested in using the AMOEBA FF. I need to equilibrate NPT and NVT before production run. However I saw in OpenMM documentation that "The virial is not calculated for any force." Can you do NPT in OpenMM with AMOEBA?

Thanks!

[Peter Eastman]

Yes. Add a MonteCarloBarostat to your system. See http://docs.openmm.org/latest/userguide ... e-coupling.

[Daniel Konstantinovsky]

Thank you! Was worried barostat wasn't supported for AMOEBA.

One more q: John Chodera wrote in a old chat "Note that there can be issues when using finite-timestep MD without Metropolization together with a Monte Carlo barostat. The MC samples from the exact Boltzmann distribution, while the MD samples from a perturbed distribution in a timestep-dependent manner. Usually, this error is small, but with AMOEBA, it caused large problems."

Would using Langevin integrator address this?

[Daniel Konstantinovsky]

Actually never mind just saw the documentation re Langevin integrator