i have had a puzzle on relax time.now i want simulation the
solidification of the metal melt droplet, i used fix nvt command like
velocity all creat 2300 32545
fix 3 all nvt 2000 300 100
Then my question is
a. In order to get the melt of metal , i set the temperature 2300
above the melt point of metal in the velocity command ,then
equilibrated in this temperature for a special time by fix nve (run
1000 timestep),is it right or valid?
b. how shoud the random seed "32545" be set? is it arbitrary ? what is
considered when it did.
c in simulation solidification process (fix 3 all nvt 2300 300
100), if i can get the temperature each timestep is a ramped value
during the run (1000) from (2300)to (300), that is we got
d what is the mean of the Tdamp(100), is it relax time? what relation
is between the relax time and the timestep? some people say the relax
time should be set in a order with timestep and <= the timestep ,why?
e Is the relax time the real time? about the timestep? then in my
inout file ,the relaxtime is 100 time untis,that is 100ps, and the
timestep is 0.1ps
f. the decrease temperature rete is (Tstart -Tend)/(run * timestep)