My system is as follows: My unit cell is a slice of a

nanowire embedded in a surrounding matrix, and the

natural lattice constant of the wire is greater than

that of the matrix. The initial state of the system

would force the lattice constant of the nanowire to be

that of the surrounding matrix, and then as the system

equilibrates, the wire would expand and induce

stresses on the matrix. The catch is that I need to

allow for some expansion on the part of the matrix as

well, so an NVE condition isn't going to be

sufficient. Note that all the materials here are

supposed to be solid semiconductors.

I was thinking of using an NPT or NPH ensemble here,

but I'm not sure if it would be appropriate to assume

atmospheric pressure or zero pressure, or even if

there might be something I can do in LAMMPS that

didn't rely on assuming a pressure. What would be a

sensible way to go here?