Dihedral angles torsion interaction

Figure 1 Schematic of the interactions between an amino group and a water showing the Lennard-Jones and electrostatic nonhonded interactions along with the bond length, bond angle, and dihedral angle (torsional) interactions.

The term representing the trigonometric dihedral-angle torsion interaction reads... 

The valence interactions consist of bond stretching, bond angle bending, and dihedral angle torsion, active in nearly all force-fields for covalent systems. The nonbonded interactions consist of van der Waals, electrostatic and hydrogen bond terms, and the form of each expression depends on the particular force-field [67,62]. 

The valence interactions consist of intramolecular bond stretching, bond angle bending, dihedral angle torsion, and inversion as shown in Figure 1. 

The first four terms represent bonded interactions, that is, bond stretching bond-angle bend U, dihedral angle torsion t/,. , and inversion interaction U. 

The energy of valence interactions accounts for bond stretching (bond), valence angle bending (angle), dihedral angle torsion (torsion), and inversion, also called out of plane interactions (oop) ... 

The first four terms represent bonded interactions, i.e., bond stretching Ubond, bond-angle bend Uangle and dihedral angle torsion Utorsion and inversion interaction Uinversion, while the last two terms are nonbonded interactions, i.e., van der Waals energy Uvdw and electrostatic energy Uelectrostatic. In the equation, are the positions of the atoms or particles specifically... 

The dihedral angle or torsional energy interaction in MM-t is of the general form of equation (12) on page 175 but explicitly includes n=l, 2, and 3 with a phase angle (j) =0 ... 

Electrostatic interaction Dihedral angle bond dipoltr-bond dipate or torsion... 

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