hybrid style for a two layers system with 4 types of atoms

Dear lammps users,
I am trying to simulate a 2layer material in which each layer includes Si and C atoms so, I have 4 types of atoms. Two types in the first layer and two types in the second layer.I use the following commands to introduce the tersoff potential between Si atoms(Si-Si) and C atoms (C-C). However I do not know how to introduce the tersoff potential between Si and C atoms.

pair_style hybrid tersoff lj/cut 12
read_data SiC2.dat
pair_coeff 12 3 lj/cut 0.004 3.212

pair_coeff * * tersoff 1 SiC.tersoff Si NULL NULL NULL
pair_coeff * * tersoff 2 SiC.tersoff NULL C NULL NULL
pair_coeff * * tersoff 3 SiC.tersoff NULL NULL Si NULL
pair_coeff * * tersoff 4 SiC.tersoff NULL NULL NULL C

Could anyone help me? Much appreciate it.

Best regards,
Nima Pirouzmand

Dear lammps users,
I am trying to simulate a 2layer material in which each layer includes Si
and C atoms so, I have 4 types of atoms. Two types in the first layer and
two types in the second layer.I use the following commands to introduce the
tersoff potential between Si atoms(Si-Si) and C atoms (C-C). However I do
not know how to introduce the tersoff potential between Si and C atoms.

pair_style hybrid tersoff lj/cut 12
read_data SiC2.dat
pair_coeff 1*2 3* lj/cut 0.004 3.212

pair_coeff * * tersoff 1 SiC.tersoff Si NULL NULL NULL
pair_coeff * * tersoff 2 SiC.tersoff NULL C NULL NULL
pair_coeff * * tersoff 3 SiC.tersoff NULL NULL Si NULL
pair_coeff * * tersoff 4 SiC.tersoff NULL NULL NULL C

Could anyone help me? Much appreciate it.

this input fragment is incorrect. your pair_coeff refers to 4
different tersoff styles in hybrid, but you only specify it once.

that said, if you have two "groups", why four pair_coeff sections and
what not simply two each containing both SI and C?

axel.

Dear Axel,

Thank you for your comment.

I thought that to add LJ interaction between Si,and C in two layers we need to have 4 type of atoms.

BR,

Nima Pirouzmand

Dear Axel,
Thank you for your comment.
I thought that to add LJ interaction between Si,and C in two layers we need
to have 4 type of atoms.

yes, but there is no contradiction. you can have two tersoff substyles
and 4 atom types.

axel.

OK. So, I put it this way,
pair_style hybrid tersoff tersoff lj/cut 12
read_data SiC2.dat
pair_coeff 12 3 lj/cut 0.004 3.212

pair_coeff * * tersoff 1 SiC.tersoff Si NULL
pair_coeff * * tersoff 2 SiC.tersoff NULL C

Correct? what about the interaction between Si and C?

BR,

Nima Pirouzmand

OK. So, I put it this way,
pair_style hybrid tersoff tersoff lj/cut 12
read_data SiC2.dat
pair_coeff 1*2 3* lj/cut 0.004 3.212

pair_coeff * * tersoff 1 SiC.tersoff Si NULL
pair_coeff * * tersoff 2 SiC.tersoff NULL C

Correct?

syntactically yes, logically no. you used to have 4 atom types. two
for each layer. what happened to those.

what about the interaction between Si and C?

i am extremely tempted to ask you to check the interaction between
your brain and your eyes. you seem to be reading what is suggested,
but not thinking about what you are doing, but rather try something
and hope that sooner or later you will hit a combination that will
work. that is not likely to happen. this is the last reply on this
thread from me.

what you need to do is straightforward to do and very logical, but you
will never learn how to solve problems logically, if i just tell you.
all you need to know is in the documentation existing examples and
what i've told you.

axel.