I have been reading the documentation and the archives re: thermodynamic integration and have a question. I would like to perform a TI in which the LJ epsilon and sigma for one atom type are changed. My reading of compute ti is I must write the potential as f(lambda) U, i.e., a scaled potential energy. I don’t see how to do this for the LJ potential unless the potential energy is written as
U =U_0 + lambda (U_1 -U_0)
with U_1 and U_0 representing the endpoints of the transformation. I do not know if it is possible to evaluate U_1 and U_0 for use in a compute ti command. My question is then: does LAMMPS have the ability to perform an alchemical transformation in which both epsilon and sigma are changed for one LJ atom type?