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[lammps-users] Coulombic energy in pair_style reax/c
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[lammps-users] Coulombic energy in pair_style reax/c


From: 殷其放 <yqf59@...1188...>
Date: Wed, 3 Jun 2015 20:12:26 +0800

Hi,
 
I am trying to convert the potential file of reax from "units real" to "units metal", because I want it to work with "pair_style comb" in a hybrid way. All energies computed by "compute reax" in "units metal" are consistent with those in "units real", except those about charges including Coulomb energy and charge equilibration energy. For example, non-zero energies calculated in units real are
 
Step PotEng          bond           atom          valence         vdW              coulomb    charge_equilibration
  0   -114958.81   -131085.71    22009.218    8133.2786    10991.359   -8764.4587   -16242.491

and energies with identical read_data file in units metal are
 
Step PotEng          bond           atom          valence         vdW              coulomb    charge_equilibration
   0   -28905.715   -5681.6967    953.95353     352.5214     476.4567   -8764.4587    -16242.491

We can see the values of coulomb and charge are the same but they should be different because of different units.
In the reax potential file [B. Narayanan et al., Modelling Simul. Mater. Sci. Eng. 2012, supplementary information], I did not find any parameters for the Coulomb's constant. I guess that this constant might be hard-coded in units real in the source code. How can I solve this problem?
 
Thanks for your help,
Qifang