Dihedral angles

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In this section, parameters for dihedral angles are introduced for the standard type of torsion potential:

$$U_{tors}(\phi) = K_{\phi}(1+\cos(M\phi-\Delta))$$ (7)

Torsional angle $\phi$ is defined as having value $180^o$ for a trans-conformation.

Other types of dihedral angle potential are supported, they can be introduced in other, optional, sections.

The first line of this section specifies the number of torsion angles of this type. Lines describing torsion potential have the following meaning for the fields:

1)-4) define atoms for the torsion angle

5) is parameter $\Delta$ in degrees

6) is the force constant $K_{\phi}$ in $kJ/mol$

7) is the multiplicity factor $M$

Multiple torsions are supported. Any torsion angle can be repeated any number of times with different parameters, and all they will be summed up in the calculations of forces and energies.