[gmx-users] warter freeze into ice when "cutoff-scheme=Verlet" and "coulombtype = cut-off "

[Mark Abraham]

Hi,

That behaviour might depend on what your starting configuration is, e.g.
what group MOL has frozen coordinates. But cut-off is anyway a ~useless
model for condensed phase of atoms with partial charges, so understanding
the issue hasn't got much value.

Mark


On Mon, May 18, 2015 at 3:58 AM niexuechuan <niexuechuan at 126.com> wrote:

> Hi everyone,
>          I found that after gromacs version 4.6, when set
> "cutoff-scheme=Verlet" and "coulombtype= cut-off", the waters in the system
> will freeze into ice.  I known that charge-groups are necessary when using
> plain cut-off electrostatics. But I'm surprised that why the waters freeze
> into ice when using plain cut-off electrostatics without charge-groups?
> Could someone explain how it happenes?
>
>
> My mdp files are like this:
>
>
> integrator               = md
> constraints              = all_bonds
> dt                       = 0.002
> nsteps                   = 50000000
> comm-mode               =None
> nstxout                  = 0
> nstvout                  = 0
> nstfout                  = 0
> nstlog                   = 25000
> nstxtcout                = 500
> xtc-precision            = 1000
> energygrps               = MOL  SOL
> nstlist                  = 1
> ns_type                  = grid
> pbc                      = xyz
> rlist                    = 1.0
> coulombtype              = cut-off
> rcoulomb-switch          = 0
> rcoulomb                 = 1.0
> vdw-type                 = cut-off
> rvdw-switch              = 0
> rvdw                     = 1.0
> Tcoupl                   = V-rescale
> nsttcouple               = -1
> tc-grps                  = MOL    SOL
> tau_t                    = 0.1    0.1
> ref_t                    = 300  300
> freezegrps               = MOL
> freezedim                = Y Y Y
>
> Thanks!
> Xuechuan
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