Tilt Angle Restriction in Lattice Custom

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1

Hello All,

I am trying to build a monoclinic crystal using the lattice custom command and LAMMPS is unable to go below 59.2 degrees or above 120.2 degress for the beta angle irrespective of the tilt factor provided. My intended beta angle is 55.04 degress.

My system is;

monoclinic unit cell with a = 12.066
                                b = 4.105
                                c = 6.913
                           alpha = 90.0
                            beta = 55.04
                         gamma = 90.0

Is this a hard restriction on the lattice command? I know such restriction exist for flip angles in NPT, but not in the lattice custom.
How do I overcome this problem? Will I need to resort to generating a read_data file and specify the h-matrix ?

Suleiman.

2

You should realize that the lattice command and triclinic boxes
are 2 separate items. You can build a custom tilted lattice in an
orthogonal box.
A lattice is just a tiling of space. Triclinic boxes have to do with
offsets in periodicity, which are often not relevant for physical
systems like a crystalline solid.

Steve