Problem with pair coefficient

Dear Lammps users,

I tried to run a problem for CSH using REAXFF (ffield_CaSiAlO_Pitman.reax) potential (. When I run it, it gave me “Incorrect args for pair coefficients (…/pair_reaxc.cpp:288)”, could you please help me?

Followings are the files

in.filename:

Lammps simulation for CSH

Initialization

units real
dimension 3
processors * * *
boundary p p p

real data

atom_style full
read_data cshdata.dat
velocity all create 300.0 5812775 dist gaussian

potential

include pot.mod

timestep 0.5
thermo 1000
thermo_style custom step dt time temp c_hT pe ke press vol density lx ly lz xy xz yz
thermo_modify format 6 %20.6f
thermo_modify format 7 %20.6f
dump 2 all custom 1000 md.lammpstrj id type q x y z
dump_modify 2 append yes sort id

Equilibration

fix 1 all npt temp 300 300 50 tri 0 0 500
run 100000
unfix 1
unfix 10

REAXFF:

ReaxFF potential

pair_style reax/c NULL checkqeq no
pair_coeff * * ffield_CaSiAlO_Pitman.reax C H O Ca Si

fix 10 all qeq/reax 1 0.0 10.0 1.0e-6 reax/c

neighbor 2.0 bin
neigh_modify every 10 check yes

log.lampps:

Reading data file …
triclinic box = (0 0 0) to (13.0342 18.5862 23.62) with tilt (0.233326 1.51513 1.15251)
1 by 1 by 1 MPI processor grid
reading atoms …
480 atoms
scanning bonds …
2 = max bonds/atom
scanning angles …
1 = max angles/atom
reading bonds …
112 bonds
reading angles …
27 angles
Finding 1-2 1-3 1-4 neighbors …
special bond factors lj: 0 0 0
special bond factors coul: 0 0 0
2 = max # of 1-2 neighbors
1 = max # of 1-3 neighbors
1 = max # of 1-4 neighbors
2 = max # of special neighbors
ERROR: Incorrect args for pair coefficients (…/pair_reaxc.cpp:288)
Last command: pair_coeff * * ffield_CaSiAlO_Pitman.reax C H O Ca Si

there is not enough information here to determine the exact error causing the error message. typically, this is due to a mismatch of the number of atom types and the number of pair coeff arguments

what i do see is a different kind of error. your data file has bonds and angles defined, but for reaxFF, there should be neither. bonds and angles are computed implicitly inside the pair style instead.

axel.

Thank you for the clarification. I have look with different examples, but all of them didn’t specify the bond angles explicitly. I was confused, may be that was the reason why it show error.
In my case, is it possible to use reaxff with such data or should I remove the bond angles and length from the data?

Thanks,
Gideon

Thank you for the clarification. I have look with different examples, but all of them didn’t specify the bond angles explicitly. I was confused, may be that was the reason why it show error.

no, the cause for the error is a different one.

In my case, is it possible to use reaxff with such data or should I remove the bond angles and length from the data?

it is better to use a “clean” data file.

axel.