Description:
-The lj/gromacs styles compute LJ and Coulombic interactions with an -additional switching function S(r) that ramps the energy and force +
The lj/gromacs styles compute shifted LJ and Coulombic interactions +with an additional switching function S(r) that ramps the energy and force smoothly to zero between an inner and outer cutoff. It is a commonly used potential in the GROMACS MD code and for the coarse-grained models of (Marrink).
R1 is the inner cutoff; Rc is the outer cutoff. The coefficients A -and B are computed by LAMMPS to perform the smoothing. The function +
R1 is the inner cutoff; Rc is the outer cutoff. The coefficients A, B, +and C are computed by LAMMPS to perform the shifting and smoothing. +The function S(r) is actually applied once to each term of the LJ formula and once -to the Coulombic formula, so there are 2 or 3 sets of A,B coefficients +to the Coulombic formula, so there are 2 or 3 sets of A,B,C coefficients depending on which pair_style is used. The boundary conditions applied to the smoothing function are as follows: S(r1) = S'(r1) = 0, -S(rc) = -F(rc), S'(rc) = -F'(rc), where F(r) is the correpsonding term -in the LJ or Coulombic function and a single quote represents a -derivative with respect to r. +S(rc) = -F(rc), S'(rc) = -F'(rc), where F(r) is the corresponding term +in the LJ or Coulombic potential energy function and a +single quote represents a derivative with respect to r.
The inner and outer cutoff for the LJ and Coulombic terms can be the same or different depending on whether 2 or 4 arguments are used in diff --git a/doc/pair_gromacs.txt b/doc/pair_gromacs.txt index 1b251856f5..344f51e963 100644 --- a/doc/pair_gromacs.txt +++ b/doc/pair_gromacs.txt @@ -35,23 +35,24 @@ pair_coeff * * 100.0 2.0 :pre [Description:] -The {lj/gromacs} styles compute LJ and Coulombic interactions with an -additional switching function S(r) that ramps the energy and force +The {lj/gromacs} styles compute shifted LJ and Coulombic interactions +with an additional switching function S(r) that ramps the energy and force smoothly to zero between an inner and outer cutoff. It is a commonly used potential in the "GROMACS"_http://www.gromacs.org MD code and for the coarse-grained models of "(Marrink)"_#Marrink. :c,image(Eqs/pair_gromacs.jpg) -R1 is the inner cutoff; Rc is the outer cutoff. The coefficients A -and B are computed by LAMMPS to perform the smoothing. The function +R1 is the inner cutoff; Rc is the outer cutoff. The coefficients A, B, +and C are computed by LAMMPS to perform the shifting and smoothing. +The function S(r) is actually applied once to each term of the LJ formula and once -to the Coulombic formula, so there are 2 or 3 sets of A,B coefficients +to the Coulombic formula, so there are 2 or 3 sets of A,B,C coefficients depending on which pair_style is used. The boundary conditions applied to the smoothing function are as follows: S(r1) = S'(r1) = 0, -S(rc) = -F(rc), S'(rc) = -F'(rc), where F(r) is the correpsonding term -in the LJ or Coulombic function and a single quote represents a -derivative with respect to r. +S(rc) = -F(rc), S'(rc) = -F'(rc), where F(r) is the corresponding term +in the LJ or Coulombic potential energy function and a +single quote represents a derivative with respect to r. The inner and outer cutoff for the LJ and Coulombic terms can be the same or different depending on whether 2 or 4 arguments are used in