Hi, I think also you mean to request CELL ABSOLUTE: > &SYSTEM > ANGSTROM > SYMMETRY > 0 > CELL > 29.0 29.0 17.5 0 0 0 > CUTOFF > 100.0 > CHARGE > 1 > &END with ABSOLUTE then you enter a, b, c without ABSOLUTE then you enter a, b/a, c/a see manual here: http://www.cpmd.org/manual/node44.html#CELL Phil