[gmx-users] FFGMX. Units of a constant.

Vitaly Chaban vvchaban at gmail.com
Mon Jun 30 17:06:34 CEST 2008


What is the units for dihedral reastaints used in FFGMX?

What confused me:
    C    O    2     0.000     167.360
    C   OM    2     0.000     167.360
    C   NT    2     0.000     167.360

x2top -h:
         -kb   real 400000  Bonded force constant (kJ/mol/nm^2)
         -kt   real    400  Angle force constant (kJ/mol/rad^2)
(!!!)    -kp   real      5  Dihedral angle force constant (kJ/mol/rad^2)

Why so big difference between the default value for x2top and the
usual values listed in ffgmxbon.itp? At the same time, constants for
bonds and angles are very close in both places.


Vitaly V. Chaban
School of Chemistry
National University of Kharkiv
Svobody sq.,4, Kharkiv 61077, Ukraine
email: chaban at univer.kharkov.ua
skype: vvchaban

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