atomic_mass= positive real number
mass 63.546 mass 26.9815 mass 55.845
This command sets the atomic mass in g/mol. The three examples are for Cu, Al, and Fe, respectively, corresponding to those in the lattice command. Note the current PyCAC code can only simulate pure metals.
The mass matrix type in the finite element calculation in the coarse-grained domain is specified in the element command.