hbond/dreiding/lj syntax

LAMMPS LAMMPS Mailing List Mirror
1

Hello,

I would like to request a small correction in the documentation:

pair_style hbond/dreiding/lj
and
pair_style hbond/dreiding/morse

have incorrect order of arguments in the syntax section.

Furthermore, the expression for hbond/dreiding/lj in the documentation
has extra 4 which is not present in the code.

Thank you,
Vaclav

2

I think today's 30May11 patch fixes these - please check?

Thanks,
Steve

3

Thank you. Yes, it's fixed.

I would like to make a comment / feature request in case the "single"
function will be modified sometimes in the future:

I wanted to use "compute group/group" to compute interaction energy
between two groups of atoms, however the "single" function as
implemented for hbond/dreiding/lj pair style cannot be used in for
"compute group/group". I think the "single" function for
hbond/dreiding/lj could be easily generalized to work with "compute
group/group".

Also, I require to know individual energy components of the pair
interaction, but "compute group/group" only returns the total energy.

Currently, I call Lammps multiple times with individual atom groups to
get the interaction energy and it's components (Coulomb, VdW, hydrogen
bond).

Best,
Vaclav

4

I wanted to use "compute group/group" to compute interaction energy
between two groups of atoms, however the "single" function as
implemented for hbond/dreiding/lj pair style cannot be used in for
"compute group/group". I think the "single" function for
hbond/dreiding/lj could be easily generalized to work with "compute
group/group".

Why doesn't it work? The latest version added a single() function.

Steve

5

Because the hydrogen bond is not symmetric. Currently implemented
single() function only works when i is donor and j acceptor. In order
for single() to work with "compute group/group", it would have to
consider both: i donor, j acceptor and j donor, i acceptor.
Furthermore, the single() function would always have to go through all
the atoms bonded to the donor atom to consider all possible hydrogen
bonds -- but currently there is a "return 0.0" statement in the middle
of the loop, which can stop summing all the energies and forces.

Best,
Vaclav

6

Maybe Tod has a suggestion on this ,as he is the
one who just implemented it.

Steve