The subroutine DIHFRC has been requested to process a form of
electrostatic potential it does not recognise.
Action:
The error arises because the integer key keyfrc has
an inappropriate value (which should not happen in the standard
version of DL_POLY_2 ). Check that the FIELD file correctly
specifies the potential. Make sure the version of DIHFRC does
contain the potential you are specifying. Report the error to the
authors if these checks are correct.