Melatonin geometries are from 
  U.R. Fogueri, S. Kozuch, A. Karton, and J.M.L. Martin, J. Phys. Chem. A 117, 2269 (2013)
and form the Melatonin52 set used in
  N. Mardirossian and M. Head-Gordon, J. Chem. Phys. 144, 214110 (2016).

Simulation cell lattice vectors / angstroms:

29.973599 0.000000 0.000000
0.000000 26.583092 0.000000
0.000000 0.000000 22.742091
