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Class: | Parameter
Parent: | Object

### Description

#### Overview

The class Parameter provides access to the MM/MD parameters. The MM/MD parameters are either global (accessible from all Molecule object) or local (only accessible from the associated molecule). The global parameter object can be retrieved by the constant Parameter::Builtin and the class method Parameter#builtin (both returns the same value). On the other hand, the local parameter object can be obtained by Molecule#parameter.

The local parameter object does not touch the global parameter, and vice versa. The only exception is Parameter#lookup method of the local Parameter object, which may look for the global parameters as directed by the options (actually it does so by default).

There are eight types of parameters; bond, angle, dihedral, improper, vdw, vdw_pair, vdw_cutoff, and element. For detailed description of these parameter types, see "Parameter types" in the ParameterRef document.

### Constant

Builtin

The instance that represents the global parameters.

### Public Class methods

builtin → Parameter

Returns Parameter::Builtin.

### Public Instance methods

angle(idx) → ParameterRef

The idx-th angle parameter record is returned.

angles → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of angle parameters. Parameter#angles[x] is equivalent to Parameter#angle(x).

bond(idx) → ParameterRef

The idx-th bond parameter record is returned.

bonds → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of bond parameters. Parameter#bonds[x] is equivalent to Parameter#bond(x).

dihedral(idx) → ParameterRef

The idx-th dihedral parameter record is returned.

dihedrals → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of dihedral parameters. Parameter#dihedrals[x] is equivalent to Parameter#dihedral(x).

element(idx) → ParameterRef
element(t1) → ParameterRef

In the first form, the idx-th element parameter record is returned. In the second form, the parameter for t1 is looked up (the last index first). t1 is a String representing the element name (up to 4 characters). Self must be a global parameter, i.e. Parameter::Builtin.

elements → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of element parameters. Parameter#elements[x] is equivalent to Parameter#element(x). Self must be a global parameter.

improper(idx) → ParameterRef

The idx-th improper parameter record is returned.

impropers → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of improper parameters. Parameter#impropers[x] is equivalent to Parameter#improper(x).

lookup(par_type, atom_types, options, ...) → ParameterRef

Find the parameter record that matches the given atom types. The parameter type is given as a String, like "bond", "angle", etc. The atom types are given either as an array of string, or a single string delimited by whitespaces or hyphens. Options are given as symbols. Valid values are `:global` (look for global parameters), `:local` (look for local parameters), `:missing` (look for missing parameters), `:nowildcard` (do not allow wildcard matching), `:nobasetype` (the base type does not match for the variant types). If neither `:global` nor `:local` is specified, it behaves as if both of these were specified.

This method is also implemented in ParEnumerable. See ParEnumerable#lookup.

nangles → Integer

Returns the number of angle parameters.

nbonds → Integer

Returns the number of bond parameters.

ndihedrals → Integer

Returns the number of dihedral parameters.

nelements → Integer

Returns the number of element parameters.

nimpropers → Integer

Returns the number of improper parameters.

nvdw_cutoffs → Integer

Returns the number of vdw cutoff parameters.

nvdw_pairs → Integer

Returns the number of vdw pair parameters.

nvdws → Integer

Returns the number of vdw parameters.

vdw(idx) → ParameterRef

The idx-th vdw parameter record is returned.

vdw_cutoff(idx) → ParameterRef

The idx-th vdw cutoff parameter record is returned.

vdw_cutoffs → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of vdw cutoff parameters. Parameter#vdw_cutoffs[x] is equivalent to Parameter#vdw_cutoff(x).

vdw_pair(idx) → ParameterRef

The idx-th vdw-pair parameter record is returned.

vdw_pairs → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of vdw pair parameters. Parameter#vdw_pairs[x] is equivalent to Parameter#vdw_pair(x).

vdws → ParEnumerable

Returns a ParEnumerable value that (formally) points to the collection of vdw parameters. Parameter#vdws[x] is equivalent to Parameter#vdw(x).