This section covers the Smit-Karaborni-Siepmann Force Field (SKS) for n-alkanes as it is implemented
into the towhee_ff_SKS file in the ForceFields directory. All of the Towhee atom types for this force field
are listed, along with a short description of their meanings.
SKS uses a 'Lennard-Jones' classical_potential and the 'Lorentz-Berthelot' classical_mixrule.
This forcefield is best used with a 13.8 Angstrom cutoff with no tail corrections and without shifting
at the cutoff. This strange set of parameters is due to a bug in the code originally used to produce
this forcefield. Please see the Erratum in the references section for more information.
The SKS forcefield was later extended to branched alkanes (SMMK Main)
and eventually replaced by the TraPPE-UA force field.
Any discrepencies (especially typos) from the published force field values are the sole
responsibility of Marcus G. Martin, and I welcome feedback on how this
implementation compares with other programs.
References for SKS
The parameters and detailed results for the SKS force field are found here.
Please note that an error was made in the code that produced the results in that paper that
essentially meant that tail corrections were not employed. Please see the following erratum
for more information.
SKS in Towhee
The official force field name for SKS in Towhee is 'SKS'. Here
I list all of the atom names for use in the towhee_input file,
along with a brief description.
Please note that the capitalization and spacing pattern is important and must be followed exactly
as listed here.
- 'CH3' methyl group (C plus 3 bonded H as a united-atom) on an n-alkane of C4 or longer.
- 'CH2' methylene group (C plus 2 bonded H as a united-atom) on an n-alkane of C4 or longer.
There are no coulombic interactions for this force field.
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