Confusion about what thermo keyword 'vol' refers to


I am confused as to what volume the thermo keyword ‘vol’ refers to. I was told that it corresponds to the size of the simulation box. However, if I define a lattice with a scale factor different than 1, it influences the value of ‘vol’, but I didn’t think the scale factor should change the size of the simulation box, just of the unit cell for the lattice. The volume does seem to scale as the simulation box stretches though, if one of the faces of the box is defined with the ‘shrink-wrap’ style. So can someone enlighten me as to exactly what geometric space ‘vol’ is calculated from?


Vol is the geometric size of the box. If you define

a 10x10x10 lattice with a small lattice spacing vs

a large lattice spacing, then the size of the box changes.