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[lammps-users] OPLSAA for lammps input using moltemplate
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[lammps-users] OPLSAA for lammps input using moltemplate


From: John Smith <johnson21smith@...24...>
Date: Fri, 21 Jul 2017 20:31:43 -0500

I am using moltemplate to generate OPLSAA forcefield input for LAMMPS. I am looking to simulate butanol, but I am confused which @atom type should be selected for the OH group.

 

Firstly, do I assume that the OH group is one unit and specify the atom as OH, using the co-ordinates for the O atom and ignoring the H while assuming that its effects are absorbed into the OH?

 

Secondly, there are many options for OH in the oplsaa.lt file as follows. Which one is the most appropriate for butanol? How do I decide this?

 

set type @atom:20 charge -0.7  # "Alcohol OH (UA)"

set type @atom:21 charge 0.435  # "Alcohol OH (UA)"

set type @atom:96 charge -0.683  # "Alcohol -OH"

set type @atom:97 charge 0.418  # "Alcohol -OH"

set type @atom:99 charge 0.145  # "Alcohol CH3OH & RCH2OH"

 

My best bet is @atom:99, but I wasn't sure about this. Please advice!

 

Thanks,

John