Please cite the following reference if the Packmol package was useful:
L. Martínez, R. Andrade, E. G. Birgin, J. M.
Martínez.
Packmol: A package for building initial configurations for molecular
dynamics simulations.
Journal of Computational Chemistry, 30(13):2157-2164, 2009.
And please also cite the following article if mentioning the packing
strategy of Packmol:
J. M. Martínez and L. Martínez.
Packing optimization for automated generation of
complex system's initial configurations for molecular dynamics and docking.
Journal of Computational Chemistry, 24(7):819-825, 2003.