fix create/bond

Dear LAMMPS users,

While I am using ‘fix bond/create’ command to create bonds, there always reports an error :

‘Expected integer parameter in input script or data file’.

I didn’t find such error in LAMMPS error list, either can I understand it. What I have done is that I first defined bond_style as fene as below,

bond_style fene

special_bond lj 0 1 1

bond_coeff 1 30.0 1.5 1.0 1.0

bond_coeff 2 30.0 2 1.0 1.0

The bond type-1 is preset in input data file, and bond type-2 is to be created by ‘fix bond/create’. In the input data file, I defined bond type = 2 in header section, but only used bond type-1 - I don’t think it is wrong.

Could any one tell me how the error comes?

Many thanks!

Sunnia

Dear LAMMPS users,

While I am using 'fix bond/create' command to create bonds, there always
reports an error :

'Expected integer parameter in input script or data file'.

I didn't find such error in LAMMPS error list, either can I understand it.

it means what it says. you provide somewhere in your input and entry
where you have a text or a floating-point number, where LAMMPS expects
an integer (i.e. a world that only contains numbers, no characters or
symbols).

What I have done is that I first defined bond_style as fene as below,

bond_style fene
special_bond lj 0 1 1
bond_coeff 1 30.0 1.5 1.0 1.0
bond_coeff 2 30.0 2 1.0 1.0

The bond type-1 is preset in input data file, and bond type-2 is to be
created by 'fix bond/create'. In the input data file, I defined bond type =
2 in header section, but only used bond type-1 - I don't think it is wrong.

your strategy to debug your input is not very effective. for something
like this, you should know at which line in the input script this
error happens, since LAMMPS processes inputs line by line and
immediately acts on any command. if you were using the very latest
version of LAMMPS, the error message would already quote the input
command causing the issue. for older versions of LAMMPS, you can run
LAMMPS with -echo both and monitor the screen output, which will echo
the input script as it is read, parsed and processed. the last line
before the crash is indicating the culprit.

axel.

Thanks - now the fix bond/create command is able to be read, but it reports another error as ‘special list size exceeded in fix bond/create’. However, I searched the error doc in LAMMPS, and it said I should add ‘extra special per atom’ in the input file in read_data part, but I cannot understand how should I add it?

The current header section in my input data file is:

804 atoms
603 bonds
603 angles
0 impropers

3 atom types
2 bond types
1 angle types
0 dihedral types
0 improper types

-15.000000 15.000000 xlo xhi
-15.000000 15.000000 ylo yhi
-15.000000 15.000000 zlo zhi

Should I insert a line between imporpers and atom types as ‘extra special per atom’?

By the way, I have set the special bond as:

special_bond lj 0 1 1 extra 2

As required by LAMMPS for using fix bond/create.

Best,

Sunnia

Thanks - now the fix bond/create command is able to be read, but it reports
another error as 'special list size exceeded in fix bond/create'. However, I
searched the error doc in LAMMPS, and it said I should add 'extra special
per atom' in the input file in read_data part, but I cannot understand how
should I add it?

read the read_data documentation, then and make suitable experiments, if needed.

axel.

Thanks - it eventually works after adding a line “10 extra bond per atom”. It is to define how many extra bonds that you would allow per atom, which means I need actually to put a number in it.