**Acknowledgements**

The author thanks Professor Libero J. Bartolotti (East Carolina University, Greenville, NC, USA) for his constant encouragement and computational support. He also thanks Professor Donald G. Truhlar (University of Minnesota, Minneapolis, MN) and Professor Rajeev K. Pathak (S. P. Pune University, Pune, India) for various discussions and most valuable suggestions during the course of this work.

This work is dedicated to the memory of author's father Dr. D. A. Kulkarni.
