comm_modify

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1

Dear Lammps-users,

I want to compute RDF with a cutoff = 20 angstroms, which is much greater than the force/potential cutoff (8 angstroms). As suggested in Lammps manual, I used the following command:

comm_modify cutoff 20.0

compute 1 all rdf 2000 * * 1 1 1 2 2 2 cutoff 20.0

fix 0 all ave/time 1 {aveStep}** **{aveStep} c_1[*] file RDF.**${T}**K.dat mode vector

fix 1 all npt temp {T}** **{T} 0.1 iso 0 0 1.0

run ${aveStep}

unfix 1

But I always get the following error:

fix 1 all npt temp {T} {T} 0.1 iso 0 0 1.0

fix 1 all npt temp 300 ${T} 0.1 iso 0 0 1.0

fix 1 all npt temp 300 300 0.1 iso 0 0 1.0

run ${aveStep}

run 10

ERROR: Compute rdf cutoff exceeds ghost atom range - use comm_modify cutoff command (…/compute_rdf.cpp:172)

Last command: run ${aveStep}

Could you please give me any advice to fix the error? Thanks in advance.

Sincerely,
Zhao

2

Dear Lammps-users,

I want to compute RDF with a cutoff = 20 angstroms, which is much greater than the force/potential cutoff (8 angstroms). As suggested in Lammps manual, I used the following command:

comm_modify cutoff 20.0

compute 1 all rdf 2000 * * 1 1 1 2 2 2 cutoff 20.0

fix 0 all ave/time 1 {aveStep}** **{aveStep} c_1[*] file RDF.**${T}**K.dat mode vector

fix 1 all npt temp {T}** **{T} 0.1 iso 0 0 1.0

run ${aveStep}

unfix 1

But I always get the following error:

fix 1 all npt temp {T} {T} 0.1 iso 0 0 1.0

fix 1 all npt temp 300 ${T} 0.1 iso 0 0 1.0

fix 1 all npt temp 300 300 0.1 iso 0 0 1.0

run ${aveStep}

run 10

ERROR: Compute rdf cutoff exceeds ghost atom range - use comm_modify cutoff command (…/compute_rdf.cpp:172)

Last command: run ${aveStep}

Could you please give me any advice to fix the error? Thanks in advance.

the cutoff to be used for comm_modify must also include the neighbor list skin distance.
so if your neighbor list skin is 1.0 angstrom and your rdf cutoff is 20.0, you need to set the communication cutoff to 21.0 instead of 20.0

axel.

3

Thanks, Axel, very much. Now it works.

Zhao