Project ID: plumID:21.041
Source: plumed.dat
Originally used with PLUMED version: 2.5
Stable: raw zipped stdout - stderr
Master: raw zipped stdout - stderr

# PLUMED works internally in kJ/nm/ps if no UNITS command is used in PLUMED input file
u_cn:     COORDINATION GROUPA=1-256 GROUPB=257-512 NN=6 MM=12 D_0=0.13 R_0=0.21 NLIST NL_CUTOFF=0.8 NL_STRIDE=5000
u_vol:    VOLUME

## Two different ions groups are distinguished by their ID e.g (1-256) for Na+ ions and (257 - 512) for Cl- ions

cn:       COMBINE ARG=u_cn     COEFFICIENTS=0.003906250000 PERIODIC=NO

# Number 0.003906250000 equals to 2.0/512, where 512 stands for the system size.
# The number is the prefactor for the average coordination number (see Eq. (1) in Phys. Rev. Let. 127, 105701 (2021))

volume:   COMBINE ARG=u_vol    COEFFICIENTS=1.953125000000 PERIODIC=NO

# Number 1.953125000000 equals to 1000/512
# where 512 stands for system size and 1000 ensures the change of units from nm^3 to A^3.

scale_cn:  COMBINE ARG=cn      PARAMETERS=7.822   COEFFICIENTS=0.12784454103809767  PERIODIC=NO
scale_vol: COMBINE ARG=volume  PARAMETERS=13.089  COEFFICIENTS=0.07640003056001222 PERIODIC=NO

# 0.127... is the inverse value of 7.822, the mean coordination number in the starting phase
# 0.076... is the inverse value of 13.089, the mean volume in the starting phase (in A^3)

easy:      CUSTOM ARG=scale_vol,scale_cn  FUNC=((-0.8151947133609164)*x+(0.5791869985664506)*y)  PERIODIC=NO
difficult: CUSTOM ARG=scale_vol,scale_cn  FUNC=((0.5791869985664506)*x+(0.8151947133609164)*y)  PERIODIC=NO

# Values above are coefficients obtained by diagonalisation of covariance matrix
# see Supplemental Material of Phys. Rev. Let. 127, 105701 (2021)

METAD ...
 LABEL=metad
 ARG=easy,difficult
 SIGMA=0.002,0.001
 HEIGHT=3.0
 PACE=500
 GRID_MIN=-1,-1
 GRID_MAX=1,1
 GRID_SPACING=0.001,0.001
... METAD

PRINT ARG=* FILE=COLVAR STRIDE=10

ENDPLUMED