[gmx-users] pure methane condensation in NVT simulation

[Ming Geng]

Dear all,
      We are trying some MD simulations with Gromacs recently. And we found
some weird phenomenon in our test. We have about 20k pure methane in a long
box(4 x 4 x 180 nm). We use OPLS-UA for methane molecule. After a 70ns of
common NVT simulation, we found the methane begin to condensate. The
simulation box shows like
        [methane|    vacuum    |       methane     |    vacuum   |methane]
.
But at the temperature we simulate, the methane should be in gas phase.

     Does anyone have any clue how this happens?




Thanks


Ming Geng
-------------------------------------------------------------
*Dr. Ming Geng（耿明）*
Institute of Geology and Geophysics, CAS

Tel: +86-10-8299-8300
Email: gengming at mail.iggcas.ac.cn