energy & forces in code

LAMMPS LAMMPS Mailing List Mirror
1

Hi lammps users,

I am trying to implement a new pair potential, and so I am going through
the source code, in particular pair_lj_cut.cpp, pair_tersoff.cpp, and
pair.cpp.

What does eflag and vflag refer to? Also, how is energy summed (i.e. which
variable)?

Thanks for your help
John

2

Hi lammps users,

I am trying to implement a new pair potential, and so I am going through
the source code, in particular pair_lj_cut.cpp, pair_tersoff.cpp, and
pair.cpp.

you should also have a look at verlet.cpp.

What does eflag and vflag refer to? Also, how is energy summed (i.e. which
variable)?

eflag is true if energies are to be evaluated, vflag if the virial is required.
using the calls to ev_tally*().

axel.

3

Thanks for the help!

I have another question about the Tersoff.cpp implementation. What is the
attractive() subroutine for? It is called after the energies for Fr(ij)
and b(ij)*Fa(ij) are summed with ev_tally(). It looks like a virial
component but I don't understand how it is applied.

Thanks again,
John

4

Thanks for the help!

I have another question about the Tersoff.cpp implementation. What is the
attractive() subroutine for? It is called after the energies for Fr(ij)
and b(ij)*Fa(ij) are summed with ev_tally(). It looks like a virial
component but I don't understand how it is applied.

that is part of the 3-body term. i don't know the tersoff implementation
that well, but the virial component is tallied later using v_tally3()
you'll have to read the sources and compare to the documentation
and probably also the reference papers for the tersoff potential...

axel.