RE: VDW energy is negative but total energy is positive

From: Bennion, Brian (Bennion1_at_llnl.gov)
Date: Mon Sep 09 2013 - 10:25:53 CDT

Is there something else in the methanol box? A protein, DNA? Methanol should not contain an improper term.
More importantly is the fact that your electrostatic term is huge for just a methanol box. That is what is driving the positive energy.

-----Original Message-----
From: owner-namd-l_at_ks.uiuc.edu [mailto:owner-namd-l_at_ks.uiuc.edu] On Behalf Of dayanidhi mohanta
Sent: Friday, September 06, 2013 9:19 PM
To: namd-l_at_ks.uiuc.edu
Subject: namd-l: VDW energy is negative but total energy is positive

Sir, i am new to NAMD and I'm using NAMD_2.9_Linux-x86_64-TCP/namd2. Sir, i have run the minimization of a methanol box (of dimension 60A: pdb file was generated using PACKMOL and the psf file using PSFGEN) for 50000 steps using NAMD. my output files show that VDW energy is negative where as the total energy is positive. Sir, i would like to know if there is some problem with my system.

I'm attaching the output of the 50000th step for your kind reference

ETITLE: TS BOND ANGLE DIHED IMPRP ELECT VDW BOUNDARY MISC KINETIC TOTAL TEMP POTENTIAL TOTAL3 TEMPAVG PRESSURE GPRESSURE VOLUME PRESSAVG GPRESSAVG

ENERGY: 50000 921.1493 571.4178 277.3650 6.8703 17646.8329 -8080.5121 0.0000 0.0000 0.0000 11343.1231 0.0000 11343.1231 11343.1231 0.0000 -2425.3588 -2425.4013 216000.0000 -2425.3588 -2425.4013

Thanking You in advance

Dayanidhi Mohanta
PhD (Chemistry)
NIT Rourkela

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