ERROR: Pair style does not support compute group/group

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Dear All,

I am using LAMMPS version 7Aug2019.

I have used the group/group command to calculate the energy transfer between water (TIP4P model) and gold (with no charge) from the following command:

compute pair water group/group Au pair yes

compute kspace water group/group Au pair no kspace yes

I have implemented the following pair style and LAMMPS has been stopped due to error.

pair_style lj/cut/tip4p/long 2 1 1 1 0.1546 10 8.5

pair_coeff 1 1 0.00 0.00

pair_coeff 2 2 0.18 3.15

pair_coeff 1 2 0.00 0.0

pair_coeff 3 3 5.0 2.9

pair_coeff 1 3 0.0 0.0

pair_coeff 2 3 1.0 3.6

The error is as follows:

ERROR: Pair style does not support compute group/group (…/compute_group_group.cpp:129)

As I have changed the pair style to a hybrid one as follows, the problem has been solved and the error did not appear anymore.

pair_style hybrid lj/cut/tip4p/long 2 1 1 1 0.1546 10 8.5 lj/cut 10

pair_coeff 1 1 lj/cut/tip4p/long 0.0 0.0

pair_coeff 2 2 lj/cut/tip4p/long 0.18 3.15

pair_coeff 1 2 lj/cut/tip4p/long 0.0 0.0

pair_coeff 3 3 lj/cut 5.0 2.9

pair_coeff 1 3 lj/cut 0.0 0.0

pair_coeff 2 3 lj/cut 1.0 3.6

Since I want to use “lj/cut/tip4p/long” for all interactions in the simulation, I will be pleased if someone can help me with this matter.

Is there any way to solve that?

Atom type 1 is Hydrogen, 2 is Oxygen and 3 is gold.

Best Regards,

Hamid

2

Dear All,

I am using LAMMPS version 7Aug2019.

I have used the group/group command to calculate the energy transfer between water (TIP4P model) and gold (with no charge) from the following command:

compute pair water group/group Au pair yes

compute kspace water group/group Au pair no kspace yes

[...]

Since I want to use “lj/cut/tip4p/long” for all interactions in the simulation, I will be pleased if someone can help me with this matter.

Is there any way to solve that?

no. the tip4p pair styles do not have the required Pair::single()
function, which is an alternate, much less efficient way to compute
forces and energies selectively for individual pairs of atoms.

the tip4p specific force computation does not happen for individual
pairs of atoms. whenever to compute forces and energies that involve
water atoms, forces due to charges are computed for the tip4p model
charge positions and then projected on actual atom positions. thus the
output of the Pair::single function would be incomplete and also would
contain forces that affect atoms outside the single pair of atoms.
thus this cannot be used in the framework of compute group/group.

you have the following two options:
- don't use the tip4p pair style, but define the water with an
explicit point M, i.e. from 4 sites instead of 3 sites. this requires
using fix rigid and thus will require a much smaller timestep as with
the tip4p pair style and fix shake.
- do your regular calculation and record the trajectory. then create a
new input, where you define only the interactions you want to monitor
and set everything else to zero (watch out for charges!) and use the
rerun command to recompute forces and energies for this particular
setup.

axel.

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