[gmx-users] positive system total-energy

Qiao Baofu qiaobf at gmail.com
Wed Mar 7 09:43:08 CET 2007


Hi David,

Thanks for your reply!

It is a pure ionic liquid system. I compared this energy result with that of
another system, found that the term of  "Coul.-recip." is very smaller (-
4664.24) than another system's  result  (-56014.1). All other terms of the
energy are in the same order of magnitute.

What does Coul.-recip mean?

PME is used for Coulomb interaction. Switch is used for LJ interaction.

1. abnormal result
Energy                      Average       RMSD     Fluct.      Drift
Tot-Drift
-------------------------------------------------------------------------------
Bond                        8121.16    129.568    129.564 0.000320592
3.20592
Angle                       16284.9    174.598    174.578 -0.00090818    -
9.0818
Ryckaert-Bell.           4489.18    147.842    144.019 -0.0115717   -115.717
LJ-14                        1169.97    34.0818    33.9909 -0.000861911   -
8.61912
Coulomb-14               2666.03    191.396    186.964 -0.0141849   -141.849
LJ-(SR)                    -32381.8    146.511      146.4 -0.0019765    -
19.765
Disper.-corr.              -2462.41    5.29279    5.28651  8.934e-05
0.8934
Coulomb-(SR)           -11046.1    213.609    210.484  0.0126112    126.112
Coul.-recip.               -4664.24     141.26    136.108  0.0130948
130.948
Potential                  -17823.3    250.663    250.472 -0.00338716   -
33.8716
Kinetic-En.                32678.4    188.545    188.545 -6.01562e-06 -
0.0601562
Total-Energy               14855.1    163.416    163.122 -0.00339318   -
33.9318
Temperature                299.965    1.73071    1.73071          0
0


2.normal results
Energy                      Average       RMSD     Fluct.      Drift
Tot-Drift
-------------------------------------------------------------------------------
Bond                        3707.66    103.252    103.238 0.000572337
5.7156
Angle                       10644.9    157.095    157.095 4.14791e-06
0.0414228
Ryckaert-Bell.           3215.44    108.937    108.932 -0.000366312   -
3.65815
LJ-14                       1314.19    29.5303    29.5302 -3.01152e-05  -
0.300743
Coulomb-14             -14049.8    17.4104    17.4061 0.000134398    1.34216
LJ-(SR)                    -11648.8    158.786     158.35 0.00408289
40.7735
Disper.-corr.              -1192.91    3.76608    3.73988 0.000153815
1.53606
Coulomb-(SR)           -31913.4    149.436    148.956  0.0041528    41.4716
Coul.-recip.               -56014.1    36.3764    36.0691 0.00163665
16.3442
Potential                  -95936.8    248.465     246.67  0.0103406
103.266
Kinetic-En.                23457.6    186.095    186.095 1.29671e-05
0.129495
Total-Energy             -72479.2    162.228    159.458  0.0103536
103.395
Temperature              399.928    3.17272    3.17272 2.21097e-07
0.00220797




2007/3/6, David van der Spoel <spoel at xray.bmc.uu.se>:
>
> Qiao Baofu wrote:
> > Hi,
> >
> > I have a 10 ns job. But when using the g_energy to calculate the
> > component of the energy, I got a positive total-energy!!
> >
> > Who can give some suggestions?  Thanks a lot!
> >
> what kind of system? do you happen to have an organic solvent?
> in that case you should subtract the self energy per molecule
>
> --
> David.
> ________________________________________________________________________
> David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
> Dept. of Cell and Molecular Biology, Uppsala University.
> Husargatan 3, Box 596,          75124 Uppsala, Sweden
> phone:  46 18 471 4205          fax: 46 18 511 755
> spoel at xray.bmc.uu.se    spoel at gromacs.org   http://folding.bmc.uu.se
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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-- 
Sincerely yours,
**********************************************
Baofu Qiao, PhD
Frankfurt Institute for Advanced Studies
Max-von-Laue-Str. 1
60438 Frankfurt am Main, Germany TEL:+49-69-7984-7529
**********************************************
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