Dear Prof Gale,
I’m using GULP to study the elastic properties of some disordered systems using a supercell approach. When trying to run supercells containing more than 1000 atoms, I get the following error in the gout file: ERROR : Unrecognised option in input = Zr1000 and no output. Is it the case that GULP won’t take inputs with more than 1000 atoms or is there a way you can recommend to work around this?
Many thanks,
Robert
Hi Robert,
The issue here isn’t the number of atoms, which can be as large as the memory of your computer will allow. The problem is the species type. GULP currently allows up to 999 species types per atomic number, which is enough for all force fields I know of (i.e. up 999 different force field parameters for atoms of the same element). My guess is that you’ve just label each atom with its number, which in GULP means you are specifying them as different species. If you just label all the Zr atoms that have the same force field type with the same number (or no number if they are all the same) then the problem will disappear.
Regards,
Julian