[gmx-users] OPLS-AA forcefield

Justin A. Lemkul jalemkul at vt.edu
Thu May 27 21:26:09 CEST 2010

Erik Marklund wrote:
> Justin A. Lemkul skrev:
>> you zou wrote:
>>> Hi everyone,
>>> I have one simple question. I don't know is there any different 
>>> between OPLS-AA forcefield and OPLS-AA/L forcefield? I think these 
>>> are different but when I use pdb2gmx tool there is no OPLS-AA 
>>> forcefield to choose.
>> There is no difference.  The presence of "/L" simply indicates it is 
>> for liquid simulations.  I am unaware of a vacuum or gas phase 
>> OPLS-AA, certainly not within Gromacs.
>> -Justin
> I think that's incorrect. The 'L' in OPLS stands for 'Liquid'. The 
> trailing /L was added when some parameters were reparameteriezd 
> (dihedrals I think) at some point, but I don't know what it stands for.

Oops, you're quite right!  My mistake.  I was thinking of the wrong L :)  The /L 
indicates the use of local MP2 (LMP2) for parameterization.


> Erik
>>> Thank you
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Justin A. Lemkul
Ph.D. Candidate
ICTAS Doctoral Scholar
Department of Biochemistry
Virginia Tech
Blacksburg, VA
jalemkul[at]vt.edu | (540) 231-9080


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