Dear all,

I am a new user of GULP and simply want to test how to define in *.lib force field library, the charges so that, only the coulomb part of the potential is being calculated. This is only for test purposes.

I prepared a *.lib file with the following contents:

species

X1 core 1

X2 core -2

coul inter 1

X1 core X1 core 1.0000000000 0.0000000000 10.0000000000 0

X1 core X2 core 1.0000000000 0.0000000000 10.0000000000 0

However, the results is:

********************************************************************************

* Output for configuration 1 *

********************************************************************************

Components of energy :

--------------------------------------------------------------------------------

Interatomic potentials = 0.00000000 eV

Monopole - monopole (real) = 0.00000000 eV

--------------------------------------------------------------------------------

Total lattice energy = 0.00000000 eV

--------------------------------------------------------------------------------

Total lattice energy = 0.0000 kJ/mol

--------------------------------------------------------------------------------

I have run the same calculation with FORCITE and I get the following output:

---- Current structure ----

Total energy : -218.449071 kcal/mol

Contributions to total energy (kcal/mol):

Non-bond energy : -218.449

Electrostatic : -218.449

So the calculation runs, the problem is that GULP is not reading the specified charges. The atomic positions are taken into account but charges (in my view) are not. Can some one tell me how to define the charges in an external file, so that I can run the a more complex calculation using a force field expression containing both coulomb and buckingham terms, for example?

Thank you,