Glushkov V. New aspects in theory and computational methods for many-body quantum systems. Applications to the electronic structure of molecules.

. Electronic structure of molecules. To develop an effective approach to solving the problems in quantum theory of molecules, which can be formulated in terms of eigenvalue problems with the orthogonality constraints imposed on the eigenvectors. The methods of investigation employ the linear operator methods in the Hilbert space, variational and many-body perturbational methods. One has been solved a variational problem for determination of excited states having the same symmetry as the ground one, the problem for off-diagonal Lagrangian multipliers and basis set optimization problems. The proposed methods and software packages based on them have advantages in a comparison with the traditional ones and are capable supporting high precision electronic excitation energies of molecules.