[gmx-users] switch problem

[Ilya Chorny]

Hello,

I am noticeing some weird behavior whith the switch coulomb type.

If I set the coulomb type to switch I get oscillations in the temperature
and if I turn on pressure coupling it gices me warnings:

Warning: pressure scaling more than 1%, mu: 0.981653 0.981653 0.981653

I equillibrated the system for at least 100 ps at NVT before turning on
pressure coupling. The Temp oscillations are present even after 100 ps. The
average Temp is correct but the oscillations are way to large. If I set
coulomptype to PME or Shift the sstem behaves just fine in all cases.

Below sre my MDP params

Also: Can one usr free_energy=yes with PME in 3.2?

Thanks in advance

Ilya

cpp                 =  /lib/cpp
integrator          =  md
dt                  = .002
nsteps              =  1000
nstlog              =  100
nstenergy           =  100
nstlist             =  1
coulombtype         =  switch
vdwtype             =  switch
rcoulomb_switch     =  1.3
rcoulomb            =  1.5
rvdw_switch         =  1.3
rvdw                =  1.5
rlist               =  1.6
pbc                 =  xyz
tcoupl              =  nose-hoover
tc-grps             =  DUM  SOL
tau_t               =  0.1 0.1
ref_t               =  300 300
gen_vel             =  yes
gen_temp            =  300
gen_seed            =  -1
free_energy         =  yes
init_lambda         =  Z
delta_lambda        =  0
sc_alpha            =  1.5
energygrps          =  SOL DUM
freezegrps          =  DUM
freezedim           =  Y Y Y
Pcoupl              =  berendsen
tau_p               =  0.5
compressibility     =  4.5e-5
ref_p               =  1.01325
;DispCorr            =  EnerPres