Hi LAMMPS USERS,
I’m runnnig one system in NPT ensemble keeping Tdamp =100 and Pdamp =1000
fix 2 all npt temp 298.15 298.15 10.0 iso 0.0 0.0 1000.0
Average Temp is not at 298.15 but instead at 320
Now I decreased the Tdamp =10, now average temperature is 298.
IS IT good to run simulations with Tdamp=10 .
ORELSE CAN anyone suggest me the better way to fix it.
Hi LAMMPS USERS,
I'm runnnig one system in NPT ensemble keeping Tdamp =100 and Pdamp =1000
fix 2 all npt temp 298.15 298.15 10.0 iso 0.0 0.0 1000.0
Average Temp is not at 298.15 but instead at 320
Now I decreased the Tdamp =10, now average temperature is 298.
IS IT good to run simulations with Tdamp=10 .
ORELSE CAN anyone suggest me the better way to fix it.
there is - by far - not enough information in your e-mail.
for example:
- does your simulation conserve energy when run with fix nve?
- what are your unit settings and your time step?
- how long is the simulation?
- is the system in equilibrium?
and so on. out of context your statements have no value.
also, what exactly is it that you want to get "fixed" and why?
axel.
Hi Axel sir,
energy is not conserved in NVE , temp is going on increasing in NVE.
Units-- REAL timestep 0.5
simulation run for 1 ns and even then AVERAGE temp was 320 K when Tdamp was 100
volume and poteng equilibrated. but I’m worried about temp.
Can I control the temperature by fix ‘temp/rescale’
and I’m using pair_style buck
Thanks in advance
Hi Axel sir,
energy is not conserved in NVE , temp is going on increasing in NVE.
and that doesn't worry you? it should!
how can you expect a simulation with
NPT or NVT to work correctly, if you
don't conserve energy in NVE.
Units-- REAL timestep 0.5
simulation run for 1 ns and even then AVERAGE temp was 320 K when Tdamp was
100
volume and poteng equilibrated. but I'm worried about temp.
equilibrated?? i don't think so. how? and
how did you know, when you can't run a
proper energy conserving MD in the first place.
rather than worry about the temperature
control, you should worried about your
basic time integration and related settings.
that you don't conserve energy in NVE,
*that* is the real problem. once you fixed
that, your temperature control issues are
likely to be solved as well.
Can I control the temperature by fix 'temp/rescale'
NOOOO!!! haven't you read on this
mailing list again and again about
what a bad idea using temp/rescale
is for almost everything.
do i need to send a message to
bala, that he has people at JNC
these days, that keep forgetting
even the basics of good practices
in MD? 
axel.
Nor do you say what units you are using. The fix npt doc
page gives rules of thumb for choosing the timescale for
Pdamp and Tdamp.
Steve