User-specified connectivity for a spring network application

I would like to implement a 2D spring network in the form of a monatomic lattice with user-specified connectivity and interactions between first and second nearest neighbors. For example, I would like the second nearest neighbors in a certain lattice direction to interact with a harmonic potential while the other second nearest neighbors don’t interact at all. Is this kind of thing possible in GULP? I see that there is a connectivity option but I’m not clear on how to use it. Thanks for any help!

Probably let GULP create the connectiviti …
Use:
dump connectivity file.grs
And study and modify this result …
I had find in this way how GULP internaly works + identifed issues with pre 6.3.1 version …

If you use a form of the “molecule” keyword (depending on whether you have charges or not) to set up bonds in the system then this should all be straightforward. First make sure that the atoms being bonded are correct (using the “bonds” keyword) in case you have unusual distances. Then you can control whether potentials act between neighbours or next nearest neighbours by adding the sub-option of “bond” (only act between directly bonded atoms) or “x12” (exclude interactions between directly bonded atoms), respectively. This assumes you have specified the cutoff for the potential such that it only acts either 1-2 or 1-3.
Regards,
Julian