[AMBER] why the same structure and same topology have different energies using CHARMM and AMBER ?

From: wliu <wliu.itcs.ecnu.edu.cn>
Date: Tue, 23 Sep 2014 22:52:11 +0800

Hi,all

I did one test want to see the energies using one same structure and
the same force field (charmm22star) but with CHARMM and AMBER software
respectively.
I use CHAMBER converted my charmm22star topology file to an Amber
one, and use AMBER calculating the step0 energy to make sure the
structure don't change. I think the energies calculated from CHARMM
should almost as AMBER's. But they have large differences. I will show
them below:

CHARMM

ENER ENR: Eval# ENERgy Delta-E GRMS
ENER INTERN: BONDs ANGLes UREY-b DIHEdrals
IMPRopers
ENER CROSS: CMAPs PMF1D PMF2D PRIMO
ENER EXTERN: VDWaals ELEC HBONds ASP
USER
---------- --------- --------- --------- ---------
---------
ENER> 0 -816.43111 0.00000 2.54110
ENER INTERN> 24.28357 55.87364 5.61896 80.62898
3.35609
ENER CROSS> -8.25999 0.00000 0.00000 0.00000
ENER EXTERN> 2.82920 -980.76157 0.00000 0.00000
0.00000
---------- --------- --------- --------- ---------
---------

AMBER

NSTEP = 0 TIME(PS) = 0.000 TEMP(K) = 361.71 PRESS =
0.0
Etot = -1031.9257 EKtot = 452.4823 EPtot =
-1484.4080
BOND = 18.7515 ANGLE = 55.8736 DIHED =
136.3547
UB = 5.6190 IMP = 3.3561 CMAP =
-8.2600
1-4 NB = 110.0799 1-4 EEL = 784.8065 VDWAALS =
-105.8670
EELEC = -1923.9725 EGB = -561.1498 RESTRAINT =
0.0000

The angle, CMAPs, ub are the same, however, the other energy terms are
different. I can't understand this result, their angle term is equal
indicating that CHARMM and AMBER are calculating the same conformation.
But why other energies have much deviation in value? I will patch my

Wei Liu
--------------------------------------
Institute of Theoretical and Computational Science
East China Normal University
ShangHai，china，200062

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Received on Tue Sep 23 2014 - 08:00:02 PDT
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