1-Dimensional case (D=1) Geometry Optimization and Conformational Generalized Simulated Annealing

Applications

We have applied the MOPAC-GSA approach with to find the possible conformations of some important molecular systems. We have also treated the barriers associated with rotations around double bonds.

The different minima were obtained by considering the group G fixed and rotating the group R around the binding G-R axis, as a rigid rotor. Here, all bond lengths and all other angles are held fixed during the rotation, and are assigned standard or experimental values. We have used, for simplicity, the (1,2) machine. If quicker convergence is required, the (1,2.9) machine can be more appropriate (see [8]).

We recall that MOPAC is a quantum chemistry program package, which contains a variety of semi-empirical approximations (Hamiltonians). In this paper, to calculate the energy (heat of formation), we have used the semi-empirical MNDO-PM3 Hamiltonian [15].

• 1-Dimensional case (D=1)
• 2-Dimensional case (D=2)