i’m a new user of gulp and i would use gulp software to create new core-shell potential for ZnO. i woud include core and shell charges of cation in the fit process so i have used the species and variables section according to the help file and as follows;
buck
zn core O shel 1956.702 0.3252 0.00000 0.000 10.000 1 1 0
buck
O shel O shel 25.000000 0.600000 36.00000 0.000 10.000 1 1 1
spring
Zn 21.228027 1
spring
O 20.228027 1
species
Zn core 2.513
Zn shel -0.513
O core 0.513
O shel -2.513
variables
charge 2
Zn core
Zn shel
end
constrain fit 1
8 charge 9 charge -1 2 1
end
however when i run the code i get the next error message:
GENERAL UTILITY LATTICE PROGRAM *
Julian Gale *
Curtin Institute for Computation *
School of Molecular and Life Sciences *
Curtin University, Western Australia *
Version = 6.1.2 * Last modified = 3rd November 2022 *
**** Unrecognised element symbol En ****
Program terminated by processor 0 in istoan
can any one help me and inform me how to set charge label in the charge sub section of the variables section
Your fitting input looks syntactically OK and if I put this through GULP then there is no error. Hence it’s likely that the problem is in the part of your input that isn’t included in your message (e.g. the structure etc).
I inserted (below) the complete input file with a small modification (I disabled the constraint option). The main problem I encountered is that the program doesn’t consider the Zn shell load as a variable, and therefore when I enable the constrain option, the Gulp program doesn’t work.
Part of the problem you have here is that the charges to be fitted should be on the same line rather than 2 different lines, though this may not ultimately matter. When fitting charges the total charge is automatically constrained to be constant (usually zero) because otherwise things would go badly wrong with the Ewald sum. Hence you don’t want to add an extra constraint for this. As a result if you specify 2 charges to be fitted then only 1 will appear in the variables list as the other one is given by the charge constraint. For the special case of fitting charges within the core-shell model on an atom, as you have, it’s more normal to use the “split” option which is designed specifically for this special case and constrains the total charge within the species.