Forces Menu
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This menu is for specification of the valence forces.

Bonds, valence angles, and tau and psi four-atom angles, the first four items, are implicitly automatic forces - that is they are specified by giving the atoms types (usually atomic numbers) with distance and angle limits. All bonds and angles with the given specifications are then located automatically by VIBRATZ.

The same types of bonds and angles may be specified as manual, in the Manual Forces group. With this method, each individual bond or angle in a set is specified by giving the sequence numbers of the generated atoms involved. These sequence numbers are not generally the same as the input atoms numbers (unless there is no symmetry). This method is not applicable to crystals or polymers. This method is more direct, and may be easier to apply for simple structures, but may lead to certain types of error, such as not specifying a complete set, or specifying sets which are not consistent with symmetry.

Bonds For specifying true valence bonds with atom types and distance limits.

Angles For specifying 3-atom valence angles with atom types and distance/angle limits.

Tau (Torsion) Angles For specifying 4-atom torsion angles with atom types and distance/angle limits.

Psi (Bond-Plane) Angles For specifying 4-atom torsion angles with atom types and distance/angle limits.

Manual Forces

Manual Bonds For specifying individual true valence bonds with generated atom numbers.

Manual Angles For specifying individual valence angles with generated atom numbers.

Manual Tau For specifying individual 4-atom torsion angles with generated atom numbers.

Manual Psi For specifying individual 4-atom torsion angles with generated atom numbers.

Urey-Bradley For specifying forces derived from X-X interaction in CXn coordination polyhedra.

Interactions - Automatic For interactions between bonds and 3-atom angles, with at least one common atom.

Interactions - Manual For interactions involving 4-atom angles, or for pairs with no atoms in common.

Write Force File Writes a file containing specifications from the above dialogs.

Read Force File Reads a file containing valence force specifications, replacing all current forces.

Use Cartesian Forces Specifies the file for reading a Cartesian atomic force matrix.

Write Cartesian File Writes a file containing forces converted to the basis of x, y and z Cartesian coordinates of each atom.