[lammps-users] question on fix box/relax

If I perform only “minimize” process, it gives a reasonable result.
But if I combine “fix box/relax” with “minimize”, it showed a somewhat strange result as follows.

Step Temp E_pair E_mol TotEng Press Volume
0 0 -7467.7533 0 -7467.7533 -22006.946
52826.485
28 0 -7467.7559 0 -7467.7559 -22007.165
52826.485
Loop time of 0.487522 on 36 procs for 28 steps with 1008 atoms

It think above pressure doesn’t include kinetic term.
If so, It seems that it failed to match system pressure to desired pressure of zero.

If the pressure include kinetic term, what should I do in detail to see pressure of no kinetic term?
Why was infomration was given for merely two steps (0 and 28 steps) and not for alll the steps of 0~28 in this output?
How can I see all the information?

I used the following input.

min_style cg
min_modify dmax {dmax} line quadratic fix aaa all box/relax aniso 0.0 minimize {etol} {ftol} {maxiter} \${maxeval}

Here, the values of dmax, etol, ftol, maxiter, and maxeval are assigned elsewhere.

What should be wrong with it you think, and what should I do for it?

Best regards,

Luke

luke,

please send text-only e-mails to mailing lists.
multi-colored text is often difficult to read.

2010/10/18 JhonY. I. <[email protected]...>:

If I perform only "minimize" process, it gives a reasonable result.
But if I combine "fix box/relax" with "minimize", it showed a somewhat
strange result as follows.

Step Temp E_pair E_mol TotEng Press Volume
0 0 -7467.7533 0 -7467.7533 -22006.946
52826.485
28 0 -7467.7559 0 -7467.7559 -22007.165
52826.485
Loop time of 0.487522 on 36 procs for 28 steps with 1008 atoms

It think above pressure doesn't include kinetic term.

a minimization is a calculation at 0K (your temp is 0), so why should
there be a kinetic contribution? lammps will still compute it,
if you first set the temperature, but what would the meaning
of that kind of minimization be? a proper representation
of a system at a given temperature can _only_ be reached
by averaging over a sufficiently large sample of representative
configurations.

If so, It seems that it failed to match system pressure to desired pressure
of zero.

If the pressure include kinetic term, what should I do in detail to see
pressure of no kinetic term?
Why was infomration was given for merely two steps (0 and 28 steps) and not
for alll the steps of 0~28 in this output?

first and last.

How can I see all the information?

RTFM!

the thermo command determines how often "thermo" output is written.

axel.

The fix box/relax doc page explains how the
minimizer handles/ignores the kinetic contribution
to the pressure.

Steve

2010/10/18 JhonY. I. <[email protected]...>: