Problem in adding new pair potential and update potential

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1

Dear all,
Currently, I am doing simulation of carbon-nickel interaction. Where the potential I used is shibuta potential. Here the link http://people.ds.cam.ac.uk/jae1001/CUS/research/nano/Shibuta_Elliott_ChemPhysLett_2012.pdf. For that, to meet my condition. I should to create a pair style cpp class. One is pair_shibuta.cpp and pair_shibuta.h.

Then I put all files inside src directory of lammps-9Dec14 (version). After that, I was do the following steps:

  1. Open cygwin terminal (I use windows 8). Then go to src of lammps.
  2. Go to lib/meam then typing
    $ make -f Makefile.gfortran
  3. Go to lib/poems then typing
    $ make -f Makefile.g++
  4. Go to src/STUBS then typing
    $ make
  5. Typing:
    make makelib // to create Makelib file, where now pair_shibuta is listed make makeshlib // to create Makeshlib file, where now pair_shibuta is listed
    make makelist make serial

Everyting is going fine. I have folder Obj_serial inside src directory and got lmp_serial.exe. Inside Obj_serial I found pair_shibuta.d and pair_shibuta.o mean shibuta potential is listed inside lmp_serial.exe. After that, I create an input file which describe interaction of carbon and nickel surface. But, I met error “invalid pair style (…force.cpp)”. When I open force.cpp file, I knew that pair_shibuta is not listed inside lmp_serial.exe at all. Based on the shibuta potential, this potential need 9 or 8 parameters.

To solve this problem, I was try to modify Morse potential. Then did the same steps like before. But, I got error “incorrect arg …” . In input file, I wrote the code (snippet)

pair_style hybrid morse 3.0 eam/fs/omp airebo/omp 9.5409 1 1
.
.
.
pair_coeff 1 2 morse 2.4673 1.3 1.8706 1.7628 0.0628 -0.5351 1 2.7 3.0

I knew this error tell to me that pair coefficient is not correct. But, when I change the code above like below

pair_style hybrid morse 3.0 eam/fs/omp airebo/omp 9.5409 1 1
.
.
.
pair_coeff 1 2 morse 2.4673 1.8706 3.0

lammps can execute. This is very strenght. How come, lmp_serial know the original code of pair_morse.cpp meanwhile I was edit it before rebuild? So, please tell me how to solve this problem. I also did the same step like above on window7 in cygwin environment. But, I met the same result as well.

Sincerely,

Ibnu Syuhada
Doctor Student of Bandung Institute of Technology, Indonesia

2

there is no way to give advice on this, since you don't provide any
details on the actual code that you wrote and what your skill level in
C++ programming is. from your description it seems that you made
mistakes in your code and particularly didn't follow exactly *all* the
steps necessary to add a new potential file to LAMMPS. there are many
ways to make mistakes, and the compilation procedure is the easiest
and least error prone step of them all.

axel.

3

IDEA: If the intention as you say is to try to modify the Morse potential I think you could try to open the actual fix.cpp for the MORSE potential and modify the variables to change an actual potential and then recompile …. Trying to implement a new potential in lammps seems something not trivial (at least at my current level of programming skills) , but certainly I bet you would need to look at the Source Code into a deeply level (something not willing to do personally). Also I want to say its terrific the amount of c++ programming you can learn by looking/browsing the LAMMPS’s Source Code ……=)

4

FWIW, with the provided code, i have no problems compiling and
including the custom pair potential style. so i cannot reproduce the
problem. it has to be something in the process of compiling.

since the compilation is done on windows, all bets are off. i would
recommend to install a virtual machine software and then use a linux
virtual machine or use a linux machine directly. development (and
debugging) is *so* much easier on linux.

axel.