Unrecognized option in input=slc on gulp 6.1

SLC potential input file

title
SLC Potential Example

specify the unit cell

cell
10.0 0.0 0.0
0.0 10.0 0.0
0.0 0.0 10.0

specify the atoms

fractional
Si 0.0 0.0 0.0
O 0.5 0.5 0.5

specify the SLC potential parameters

pair_style slc
pair_coeff * * 1 1 8.0 0.1

specify the optimization parameters

optimise
cycles = 100
convergence_energy = 1e-6
convergence_force = 1e-4
start

!!!
!! ERROR : Unrecognised option in input = slc
!! : Error is apparently on line 3
!!!

Program terminated by processor 0 in inword

STOP GULP terminated with an error

How do I rectify this?

Thread closed due to inactivity, please open a new thread to address related issues.