[Towhee-users] regarding vibcoeff(1) values in towhee

[Pragati A S. <pa....@nc...>]

Dear all,

I want to calculate solubility of CO2 in a polymer system. I have used OPLS forcefield for the polymer and prepared an equilibrated system using gromacs. I want to use the same forcefield and system in towhee. But I found out that for the same atomtypes of OPLS, towhee vibcoeff(1) values does not match with the bond constant values of opls in gromacs. For standard harmonic potential, vibcoeff(1) should be equal to "kb" values of gromacs opls ff. But it is not the same. e.g
towhee:
C CA bond coefficient
0.141900 (should denote bond length)
0.2360085854e+06  ( should denote bond constant, vibcoeff(1))

gromacs opls forcefield
i j b   kb
C   CA 0.14900 334720.0

If vibcoeff values in towhee are in kcal/mol and kb values in gromacs are in kj/mol. Still I could not get same values after conversion.


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