AB Initio Prediction of Stable Confomeric Polymorphs of Benzocaine Molecule- a Local Anaesthatic Molecule

Abstract

An ab initio methodology to predict the crystal structures of thermodynamically stable polymorphs of benzocaine within the least energy region of energy landscape by analyzing the local minima from the initial gas phase optimization initiated through the flexible torsion using MP2/6-31G(d,p) method. The global search for the hypothetical dense packing for the structures within the energy penalty region of the local minima have revealed the possible stable conformers under a repulsion alone potential field. The generated hypothetical dense packings from the global search were selected for lattice minimization using the repulsion – dispersion potential field to authenticate the stability. The stability and the characteristics of the generated structures were analyzed from the comparative hydrogen bond analysis and second derivative properties with the known experimental polymorphs. The morphological studies of the global minima of benzocaine molecule from the valid lattice energy landscape was studied in detail to find the morphological important lattice.