Hi Xue If you want to contact the VCSGCMC-LAMMPS authors, you can create an account at https://gitlab.com. Then log in to your account. Then go to this web page: https://gitlab.com/materials-modeling/vcsgc-lammps/-/issues And click on the button to create a “new issue”. This is how programmers usually report bugs in (someone else’s) software. If you need help setting up your s…