I have got two questions here:
When performing simulation using LJ potential, I wrote this line in the input file
“velocity all create 3.0 …”.
But the output temperature during the simulation is about 1.6.
I tried other temperatures, the result temperature is slightly above one half of the previously set value.
I just wonder why is this happen?
I have read some explainations about the concept “reduced units”, but haven’t yet get a complete understanding of it.
As there are three basic units used to derive other units.
The mass unit is the weight of the atom,
the sigma (length unit) is around the diameter of the atom,
the value of epsilon(energy unit) divided by k is around the critical temperature of the atom(e.g. Ar or Xe)
Besides, is there any relationship between the time unit calculated with these units and the timestep employed in the simulation?
Am I right? Can anyone show me exactly how are the value of the basic units derived?
These two questions maybe quite simple, but are important in the way of my learning.
Any reply is greatly appreciated.
Wuhan Univ., China
May 23, 2007