how to use tip4p water model for big simulation box?

Dear all,

I want to simulate water with tip4p model with long-range Coulombic solver . for small simulation box (404060)A^3 there is no problem. but for big simulation box (10010050) system give error.
ERROR: Non-numeric pressure - simulation unstable (…/fix_nh.cpp:1023)
my ensembles is npt at 300 temp and 1.0 Pressure. unite is real.

thanks alot.

mousavi

Dear all,
I want to simulate water with tip4p model with long-range Coulombic solver
. for small simulation box (40*40*60)A^3 there is no problem. but for big
simulation box (100*100*50) system give error.
ERROR: Non-numeric pressure - simulation unstable (../fix_nh.cpp:1023)
*my ensembles is npt at 300 temp and 1.0 *Pressure. unite is real.

​this is not likely due to using tip4p per se but rather due to a bad
choice of parameters, e.g. for the nose-hoover barostat or thermostat or
errors in force field parameters.
larger systems allow for a wider range of fluctuations (more variety in
amplitudes and frequencies) and thus symptoms of bad simulation parameters,
that are suppressed in smaller systems, can be exposed.

axel.​