1. Institute of Applied Analysis and Numerical Simulation, Universität Stuttgart, Pfaffenwaldring 57, D-70569, Stuttgart, Germany
2. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 13, I-56124 Pisa, Italy
3. Gaussian, Inc., 340 Quinnipiac Street Building 40, Wallingford, Connecticut 06492, United States