error with hybrid pairstyle

Hello everyone,

my system consists of 6 different atom types out of those 4 are Carbon and the other two are B and N. I wanted to implement hybrid pair_style but always get an (error : Incorrect args for pair coefficients (pair_tersoff.cpp:273)).

I tried a lot of different ways but couldnot figure out the error. Even the manual couldnot help me.

What am i doing wrong?? Please help.

pair_style hybrid tersoff lj/cut 5.00
pair_coeff 1 1 tersoff C.tersoff C
pair_coeff 2 2 tersoff C.tersoff C
pair_coeff 3 3 tersoff C.tersoff C
pair_coeff 4 4 tersoff C.tersoff C
pair_coeff 3 4 tersoff C.tersoff C
pair_coeff 5 6 tersoff BN.tersoff B N
pair_coeff 1 2 lj/cut 2.86 3.46 2.0
pair_coeff 3 4 lj/cut 2.86 3.46 2.0

Regards,

Bibek Adhikari

University of Stuttgart
Germany

Even the
manual couldnot help me.

Then you haven't read the doc page for
the pair tersoff command carefully. You have
to do something like

pair_coeff * * tersoff C.tersoff C C C C NULL NULL

Steve

Dear Steve and others,

Thank you for your help. After your suggestion I tried something like this but I still get the error

(Error: all pair coeffs are not set)

pair_style hybrid tersoff lj/cut 5.0

pair_coeff * * tersoff C.tersoff C C C C NULL NULL
pair_coeff * * tersoff B.tersoff NULL NULL NULL NULL B NULL
pair_coeff * * tersoff N.tersoff NULL NULL NULL NULL NULL N
pair_coeff 1 2 lj/cut 2.86 3.46
pair_coeff 3 4 lj/cut 2.86 3.46
pair_coeff 5 6 lj/cut 3.0 2.8

i also tried like this

and i still get the error

(Pair coeff for hybrid has invalid style)

pair_style hybrid tersoff lj/cut 5.0
pair_coeff * * tersoff C.tersoff C C C C NULL NULL
pair_coeff * * tersoff B.tersoff NULL NULL NULL NULL B NULL
pair_coeff * * tersoff N.tersoff NULL NULL NULL NULL NULL N
pair_coeff 1 2 lj/cut 2.86 3.46
pair_coeff 1 3 none
pair_coeff 1 4 none

pair_coeff 1 5 lj/cut 3.0 2.8
pair_coeff 1 6 none
pair_coeff 2 3 none
pair_coeff 2 4 none
pair_coeff 2 5 ljcut 3.0 2.8
pair_coeff 2 6 none
pair_coeff 3 4 lj/cut 2.86 3.46

pair_coeff 3 5 none
pair_coeff 3 6 lj/cut 3.0 2.8
pair_coeff 4 5 none
pair_coeff 4 6 lj/cut 3.0 2.8
pair_coeff 5 6 lj/cut 3.0 2.8

Could you please help again.

Thanks

Bibek Adhikari
University of Stuttgart
Germany

Dear Steve and others,

Thank you for your help. After your suggestion I tried something like this
but I still get the error

(Error: all pair coeffs are not set)

which is a proper message. you have pairs of atom types without an
interaction set. this is required. overall, you model seems to be
*very* strange, and i would doubt that it will give meaningful
results. i would strongly recommend before even trying simulations
with such a complex force field, to first study partial systems and
validate that the parameters give reasonable results. with a complex
system, this kind of validation is near impossible.

axel.

I still don’t know what you are trying to do.

If types 1-4 are C, 5 is B, 6 is N, and you
want to use 3 different Tersoff files for those elements,
then you need to list “tersoff” 3 times in the pair_style
command, and then use this kind of syntax for 3 pair_coeff

commands:

pair_coeff * * tersoff N C.tersoff C C C C NULL NULL

where N = 1,2,3

This is all explained on the pair hybrid doc page, with

an example.