I’m using the tip4p water model for simulating pure water at room temperature and 1 atm pressure. After successfully running for about 500 ps it quitted by giving “ERROR on proc 2: TIP4P hydrogen is missing” error message. When I look at the pair_lj_cut_coul_long_tip4p.cpp and pppm_tip4p.cpp subroutines, this error message is expected if the O atom of a water molecule is not correctly bonded to 2 successive H atoms, which should not have happened for my case since nothing has changed during the run. I’m wondering if there is any other hidden reason that is not clear to me.
Thank you.
Yeneneh.
I suppose you can also get that message if the atom that is supposed to be there has gotten “lost”; in that case, it can’t find the H atom on the processor, so it fails at that point and throws up the error message you see there.
–AEI
I’m using the tip4p water model for simulating pure water at room
temperature and 1 atm pressure. After successfully running for about 500 ps
it quitted by giving “ERROR on proc 2: TIP4P hydrogen is missing” error
message. When I look at the pair_lj_cut_coul_long_tip4p.cpp and
pppm_tip4p.cpp subroutines, this error message is expected if the O atom of
a water molecule is not correctly bonded to 2 successive H atoms, which
should not have happened for my case since nothing has changed during the
run. I’m wondering if there is any other hidden reason that is not clear to
me.
this could be cause by the same type of problems
that usually cause the "lost atoms" errors, i.e. atoms
moving too fast due to bad physics or inappropriate
choice of parameters. my first recommendation would
be to run in small chunks and look for "Dangerous builds"
i.e. neighbor list updates with atoms that have moved
very far but not yet too far to be "lost". also, in general,
i would try to use less "aggressive" run parameters
and see, if the problem re-occurs.
cheers,
axel.