2006-09-22 00:22:34 +08:00
|
|
|
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
|
|
|
|
|
|
|
|
|
|
:link(lws,http://lammps.sandia.gov)
|
|
|
|
|
:link(ld,Manual.html)
|
|
|
|
|
:link(lc,Section_commands.html#comm)
|
|
|
|
|
|
|
|
|
|
:line
|
|
|
|
|
|
|
|
|
|
temper command :h3
|
|
|
|
|
|
|
|
|
|
[Syntax:]
|
|
|
|
|
|
|
|
|
|
temper N M temp fix-ID seed1 seed2 index :pre
|
|
|
|
|
|
|
|
|
|
N = total # of timesteps to run
|
|
|
|
|
M = attempt a tempering swap every this many steps
|
|
|
|
|
temp = initial temperature for this ensemble
|
|
|
|
|
fix-ID = ID of the fix that will control temperature during the run
|
|
|
|
|
seed1 = random # seed used to decide on adjacent temperature to partner with
|
|
|
|
|
seed2 = random # seed for Boltzmann factor in Metropolis swap
|
|
|
|
|
index = which temperature (0 to N-1) I am simulating (optional) :ul
|
|
|
|
|
|
|
|
|
|
[Examples:]
|
|
|
|
|
|
|
|
|
|
temper 100000 100 $t tempfix 0 58728
|
|
|
|
|
temper 40000 100 $t tempfix 0 32285 $w :pre
|
|
|
|
|
|
|
|
|
|
[Description:]
|
|
|
|
|
|
|
|
|
|
Run a parallel tempering (replica exchange) simulation of multiple
|
|
|
|
|
ensembles of a system on multiple partitions of processors. The
|
|
|
|
|
processor partitions are defined using the -partition command-line
|
2007-02-10 05:37:30 +08:00
|
|
|
switch (see "this section"_Section_start.html#2_6). Each ensemble's
|
2006-09-22 00:22:34 +08:00
|
|
|
temperature is typically controlled at a different value by a fix with
|
|
|
|
|
ID {fix-ID} that controls temperature. Possible fix styles are
|
|
|
|
|
"nvt"_fix_nvt.html, "npt"_fix_npt.html, and
|
|
|
|
|
"temp/rescale"_fix_temp_rescale.html. The desired temperature is
|
|
|
|
|
specified by {temp}, which is typically a variable previously set in
|
|
|
|
|
the input script, so that each partition is assigned a different
|
|
|
|
|
temperature. See the "variable"_variable.html command for more
|
|
|
|
|
details. For example,
|
|
|
|
|
|
|
|
|
|
variable t world 300.0 310.0 320.0 330.0 :pre
|
|
|
|
|
|
|
|
|
|
As the tempering simulation runs for {N} timesteps, a swap between
|
|
|
|
|
adjacent ensembles will be attempted every {M} timesteps. If {seed1}
|
|
|
|
|
is 0, then the swap attempts will alternate between odd and even
|
|
|
|
|
pairings. If {seed1} is non-zero then it is used as a seed in a
|
|
|
|
|
random number generator to randomly choose an odd or even pairing each
|
|
|
|
|
time. Each attempted swap of temperatures is either accepted or
|
|
|
|
|
rejected based on a Boltzmann-weighted Metropolis criterion which uses
|
|
|
|
|
{seed2} in the random number generator.
|
|
|
|
|
|
|
|
|
|
The last argument {index} is optional and is used when restarting a
|
|
|
|
|
tempering run from a set of restart files (one for each replica) which
|
|
|
|
|
had previously swapped to new temperatures. The {index} value (from 0
|
|
|
|
|
to N-1, where N is the # of replicas) identifies which temperature the
|
|
|
|
|
replica was simulating on the timestep the restart files were written.
|
|
|
|
|
Obviously, this argument must be a variable so that each partition has
|
|
|
|
|
the correct value. Set the variable to the {N} values listed in the
|
|
|
|
|
log file for the previous run for the replica temperatures at that
|
|
|
|
|
timestep. For example if the log file listed
|
|
|
|
|
|
|
|
|
|
500000 2 4 0 1 3 :pre
|
|
|
|
|
|
|
|
|
|
then a setting of
|
|
|
|
|
|
|
|
|
|
variable w proc 2 4 0 1 3 :pre
|
|
|
|
|
|
|
|
|
|
would be used to restart the run with a tempering command like the
|
|
|
|
|
example above with $w as the last argument.
|
|
|
|
|
|
|
|
|
|
[Restrictions:] none
|
|
|
|
|
|
|
|
|
|
[Related commands:]
|
|
|
|
|
|
|
|
|
|
"variable"_variable.html
|
|
|
|
|
|
|
|
|
|
[Default:] none
|
