Electronic structure theory,

Although a separation of electronic and nuclear motion provides an important simplification and appealing qualitative model for chemistry, the electronic Sclirodinger equation is still fomiidable. Efforts to solve it approximately and apply these solutions to the study of spectroscopy, stmcture and chemical reactions fonn the subject of what is usually called electronic structure theory or quantum chemistry. The starting point for most calculations and the foundation of molecular orbital theory is the independent-particle approximation. 

Electronic structure theory describes the motions of the electrons and produces energy surfaces and wavefiinctions. The shapes and geometries of molecules, their electronic, vibrational and rotational energy levels, as well as the interactions of these states with electromagnetic fields lie within the realm of quantum stnicture theory. 

In the most connnonly employed mean-field models [25] of electronic structure theory, the configuration specified for study plays a central role in defining the mean-field potential. For example, the mean-field... 

Schlegel H B 1995 Modem Electronic Structure Theory ed D R Yarkony (Singapore World Scientific) oh 8... 

Pulay P 1995 Analytioal derivative teohniques and the oaloulation of vibrational speotra Modem Electronic Structure Theory yo 2, ed D R Yarkony (Singapore World Soientifio) pp 1191-240 Muoh of the early work is desoribed in ... 

Helgaker T, J0rgensen P and Olsen J 1999 Electronic Structure Theory (New York Wiley)... 

Yarkony D R (ed) 1995 Modern Electronic Structure Theory (Singapore World Soientifio)... 

Dunning T FI Jr and Flay P J 1977 Gaussian basis sets for moleoular oaloulations Methods of Electronic Structure Theory vo 3, ed FI F III Sohaefer (New York Plenum) pp 1-27... 

Sehaefer H F III, Thomas J R, Yamaguehi Y, Deleeuw B J and Vaeek G 1995 The ehemieal applieability of standard methods in ah initio moleeular quantum meehanies Modern Electronic Structure Theory vol 2, ed D R Yarkony (Singapore World Seientifie) pp 3-54... 

Professor Bartlett brought the CC method, developed earlier by others, into the mainstream of electronic structure theory. For a nice overview of his work on the CC method see ... 

Olsen J and J0rgensen P 1995 Time-dependent response theory with applications to self-consistent field and multiconfigurational self-consistent field wave functions Modern Electronic Structure Theory vo 2, ed D R Yarkony (Singapore World Scientific) pp 857-990... 

Full quantum wavepacket studies on large molecules are impossible. This is not only due to the scaling of the method (exponential with the number of degrees of freedom), but also due to the difficulties of obtaining accurate functions of the coupled PES, which are required as analytic functions. Direct dynamics studies of photochemical systems bypass this latter problem by calculating the PES on-the-fly as it is required, and only where it is required. This is an exciting new field, which requires a synthesis of two existing branches of theoretical chemistry—electronic structure theory (quantum chemistiy) and mixed nuclear dynamics methods (quantum-semiclassical). 

K. Andersson and B. Roos, in Modem Electronic structure theory, D. Yaikony, ed.. World Scientific, Singapore, 1995, pp. 55-109. 

Schaeffer H F III (Editor) 1977. Applications of Electronic Structure Theory. New York, Plenum Press. Schaeffer H F III (Editor) 1977. Methods of Electronic Structure Theory. New York, Plenum Press. Stei. art J J P 1990. MOP AC A Semi-Empirical Molecular Orbital Program. Journal of Computer-Aided Molecular Design 4 1-45. 

Szabo A and N S Ostlund 1982. Modem Quantum Chemistry. Introduction to Advanced Electronic Structure Theory. New York, McGraw-Hill. 

To provide further insight why the SCF mean-field model in electronic structure theory is of limited accuracy, it can be noted that the average value of the kinetic energy plus the attraction to the Be nucleus plus the SCF interaction potential for one of the 2s orbitals of Be with the three remaining electrons in the s 2s configuration is ... 

---