cp2k/data/forcefield_section/H2O/SPCE.sec
2025-09-08 11:51:25 +02:00

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# SPC/E water
# H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987)
# https://doi.org/10.1021/j100308a038
# Note: This force field requires a correpsonding &G3X3 constraint section
# in &MOTION / &CONSTRAINT
# Alternatively, an unconstrained flexible variant of this force field can be defined
# by setting the K parameters in the sections &BEND and &BOND to non-zero values.
# Usage examples can be found in the folder cp2k/tests/Fist/regtest-water/.
&FORCEFIELD
&BEND
ATOMS HW OW HW
K [kcalmol*rad^-2] 0.0
KIND harmonic
THETA0 [deg] 109.47
&END BEND
&BOND
ATOMS OW HW
K [kcalmol*Angstrom^-2] 0.0
KIND harmonic
R0 [Angstrom] 1.000
&END BOND
&CHARGE
ATOM OW
CHARGE -0.8476
&END CHARGE
&CHARGE
ATOM HW
CHARGE +0.4238
&END CHARGE
&NONBONDED
&LENNARD-JONES
ATOMS HW HW
EPSILON [kcalmol] 0.0
SIGMA [Angstrom] 1.0
RCUT [Angstrom] 12.0
&END LENNARD-JONES
&LENNARD-JONES
ATOMS OW HW
EPSILON [kcalmol] 0.0
SIGMA [Angstrom] 1.0
RCUT [Angstrom] 12.0
&END LENNARD-JONES
&LENNARD-JONES
ATOMS OW OW
EPSILON [kJmol] 0.65016958
SIGMA [Angstrom] 3.16555789
RCUT [Angstrom] 12.0
&END LENNARD-JONES
&END NONBONDED
&END FORCEFIELD