plumed_ex1.dat

# Specify that we are in natural units
UNITS NATURAL

# Retrieve the value of the potential energy
ee: ENERGY
# Retrieve the 3 cell vectors
cell: CELL
# Compute the square moduli of three cell vectors
aaa2: COMBINE ARG=cell.ax,cell.ay,cell.az POWERS=2,2,2 PERIODIC=NO
bbb2: COMBINE ARG=cell.bx,cell.by,cell.bz POWERS=2,2,2 PERIODIC=NO
ccc2: COMBINE ARG=cell.cx,cell.cy,cell.cz POWERS=2,2,2 PERIODIC=NO
# Compute the moduli of the three cell vectors
aaa: CUSTOM ARG=aaa2 FUNC=sqrt(x) PERIODIC=NO
bbb: CUSTOM ARG=bbb2 FUNC=sqrt(x) PERIODIC=NO
ccc: CUSTOM ARG=ccc2 FUNC=sqrt(x) PERIODIC=NO

# Print the energy and the moduli of the three cell vectors
PRINT ARG=ee,aaa,bbb,ccc FILE=colvar STRIDE=10