Lammps2001 question

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1

Hi my name is bryan and I have a question regarding lammps2001.

In the program, when you run a restart of an NPT run with another NPT run, it appears to not be a perfect restart. What I have noticed with my runs is that when using LJ configuration, the restart pressure does not match the final pressure of the previous run. Whats the reason for this? Shouldn’t they match?

One other thing on the matter is when using real conditions, the restart of an NPT with an NPT also has discontinuous values for Ecoul, Elong, Ebond, Volume, Evdwl. Why does this happen also? Shouldn’t it be a perfect restart? When you run NVT runs the restart values are perfect but when an NPT continues an NPT those 5 values do not match the final values of the the previous. IE step 500 on run 1 has certain values, but run 2 at step 500 does not have the same value.

Was just wondering the reason and how significant this problem is to the overall data since all the other measured values match up except for those 5?

2

Well, I never run the earlier Fortran code anymore, but you didn't
say if there was anything else defined in your input script
that influences the pressure, like SHAKE or other constrataints
that remove degrees of freedom and hence affect the pressure.

It can be hard to match those exactly on successive runs. The
current LAMMPS does a better job of this.

If the difference is minor, and the 2nd run stays equilbrated
where the first run left off, then I wouldn't worry about it.

Steve