Problem in β-HMX simulation

Dear lammps users,

I am working on the simulation of β-HMX, which is monoclinic cell. The
cell parameters are:
cell_length_a 6.54
cell_length_b 11.05
cell_length_c 8.7
cell_angle_alpha 90
cell_angle_beta 124.3
cell_angle_gamma 90

So, I need to use non-orthogonal simulation box, and according to the
lammps manual, the calculated xz is -4.9027, which is not within
-(xhi-xlo)/2 and +(yhi-ylo)/2, I can not run simulation. Is there any
mistake here? If not, does it mean lammps can not do simulation about
β-HMX because of the large tilt factor? And is there any suggestion
for me?
Thank you very much.


no, you can do it. There are many values of xz which are
all equivalent geometrically and differ by multiples of (xhi-xlo). So choose
one that is within the range LAMMPS allows as input.
See section 6.12 of the manual for more details.