# Question about temperature fluctuation

Dear all,

I am a newbie for MD and use lammps-1Feb14 to run the example of reax/c/CHO.

The temperature fluctuates as follow: are they acceptable?
The corresponding temperature related keyword is

fix 1 all nve
fix 2 all qeq/reax 1 0.0 10.0 1e-6 param.qeq
fix 3 all temp/berendsen 500.0 500.0 100
output:

Step Temp E_pair E_mol TotEng Press
0 0 -10226.557 …
100 54.052007 -10207.393 …
200 134.81179 -10200.411 …
300 140.9124 -10177.136 …
400 254.70102 -10189.927 …
500 228.22249 -10162.396 …
600 393.48829 -10197.284 …
700 305.82736 -10156.708 …
800 375.95619 -10170.288 …
900 361.59017 -10155.847 …
1000 445.45645 -10176.6 …
1100 475.47017 -10180.12 …
1200 406.77222 -10155.495 …
1300 461.0586 -10167.122 …
1400 408.16084 -10148.622 …
1500 514.42637 -10178.336 …
1600 432.22679 -10151.169 …
1700 521.10069 -10175.61 …
1800 409.70904 -10138.799 …
1900 481.86412 -10160.153 …
2000 423.59857 -10138.53 …
2100 520.95339 -10169.164 …
2200 477.25036 -10153.099 …

Any comments will be appreciated.

Youzhao Lan

Dear all,
I am a newbie for MD and use lammps-1Feb14 to run the example of reax/c/CHO.
The temperature fluctuates as follow: are they acceptable?

there are a few problems with this kind of question. fist of all, you
are asking for an opinion, but findings should not depend on a
majority vote, but on scientifically justified parameters. please also
note that this is not really a LAMMPS question but a question about
basic MD. thus a suitable explanation should first be looked for in
related text books (on MD and statistical mechanics). that all being
said, the question comes up frequently and has been discussed in the
past, so please have a look at the mailing list archives and look up
those previous discussions as well.

axel.