THE STATE-SPECIFIC APPROACH TO THE SOLUTION OF PROBLEMS OF ELECTRONIC-STRUCTURE AND DYNAMICS INVOLVING EXCITED-STATES

If, in conjunction with suitable computational methods, attention is g iven to the state-specific choice and optimization of function spaces, especially when studying excited states, the accuracy of the descript ion of electronic structure and of the results of computation of prope rties increases, while the complexity of the many-electron problem is reduced significantly. These facts allow the consistent understanding of the interplay between major features of electronic structure acid p roperties or processes, as well as the practical numerical solution of computationally very demanding problems (e.g., solution of the multie lectron time-dependent Schrodinger equation). This is the conclusion f rom a number of applications of the state-specific approach(SSA) to th e analysis and calculation of stationary and nonstationary states, in the absence or presence of external electromagnetic fields. A review i s given of the basic features of the various formalisms that have been employed within the SSA for the solution of problems of electronic st ructure and dynamics. In addition, I comment, via specific examples, o n the computation of the Fermii-Sea wavefunctions for strongly mixed s tates and of valence-Rydberg-continuum interactions. (C) 1996 John Wil ey & Sons, Inc.