c:   COORDINATION GROUPA=1 GROUPB=2 SWITCH={RATIONAL R_0=1.3 D_MAX=2.6 NOSTRETCH}
cs:  COORDINATION GROUPA=1 GROUPB=2 SWITCH={RATIONAL R_0=1.3 D_MAX=2.6}
csn:  COORDINATION GROUPA=1 GROUPB=2 SWITCH={RATIONAL R_0=1.3 D_MAX=2.6} NUMERICAL_DERIVATIVES

PRINT ...
  ARG=c,cs
  FILE=COLVAR
... PRINT

DUMPDERIVATIVES ARG=c,cs FILE=deriv FMT=%8.4f

# this has been used to debug derivatives
# I don't use it in regtest since it fails doe to numerical noise (0.0 vs -0.0)
# DUMPDERIVATIVES ARG=c,cs,csn FILE=deriv FMT=%8.4f

ENDPLUMED

