type type force-constant/2 distanceANGLE (or THETA)
type type type force-constant/2 angleDIHEDRAL (or PHI)Note: angle in degrees, but force constant in Kcal/(mol*rad2).
type type type type barrier/2 periodicity phaseIMPROPER (or IMPHI)Wildcard usage: X may be used as a type wildcard. Two types of specifications can be used: A-B-C-D (all four types specified) and X-A-B-X (wildcard for first and last type). Specifications without wildcards take precedence over wildcard specifications, later specifications take precedence over earlier specifications. For multiple periodicity terms, all specifications must be of the same wildcard type. If periodicity is 0, the term will always be treated as an additive energy constant in Minimax (different from CHARMM).
type type type type force-constant/2 periodicity phaseWildcard usage: X may be used as a type wildcard. Five types of specifications can be used: A-B-C-D (all four types specified) , A-X-X-B (wildcards for the middle two types), X-A-B-C (wildcard for the first type), X-A-B-X (wildcard for first and last type) and X-X-A-B (wildcards for the first two types) . The precedence order between the five types of wildcard specifications is the order in which they are listed in the previous sentence. Later specifications take precedence over earlier specifications. Only terms with periodicity 0 are allowed in Minimax (different from CHARMM).
NBOND
(or NONBONDED) [options...]
type alpha emin rmin [ alpha14 emin14 rmin14 ]NBFIXWildcard usage: wildcards (* any number of any, % single any, # any number of digits, + single digit) may be used in types. Backslash may be used to 'quote' wildcards. Later specifications take precedence over earlier specifications, regardless of the level of wildcard usage. The parameter alpha is the atomic polarizability. If emin is negative, Lennard-Jones coefficients are determined from emin and rmin, using the usual combination formulae to derive coefficients for mixed type interactions. If emin is positive, it is interpreted as the effective number of electrons, and the Slater-Kirkwood formula is used to compute the Lennard-Jones coefficients. If the 1-4 parameters are left unspecified, they default to the normal non-bonded parameters. 1-4 parameters are used only if NBXMOD is 5 (-nbx 5 option in Minimax). In real CHARMM, the NBOND keyword may be followed by a set of options (cutoff, nbxmod, shifting, switching,...). If the last character of the NBOND command is a dash (-) options continue on the next line. Options are ignored by Minimax, which uses command line options instead.
type type emin rmin [ emin14 dmin14 ]HBONDThe NBFIX parameters allow the specification of individual atom type VDW pair interactions. The same wildcard rules apply as for the NBOND parameters. In case of duplicate specifications, the last specification takes precedence. emin must not be non-positive. The specification of the 1-4 parameters is optional: they default to the normal non-bonded parameters.
type type emin dminHydrogen bond parameters. The same wildcard rules apply as for the NBOND parameters. In case of duplicate specifications, the last specification takes precedence. emin must not be non-positive. Minimax does not implement the hydrogen bond energy term, which is not needed in modern CHARMM parameter sets. HBOND parameters are ignored by Minimax.
END marks
the end of the parameter specifications. Everything in the file after this
keyword will be ignored.
Example of a CHARMM parameter file.