Convergence and computational efficiency enhancements in the iterative solution of the G-particle-hole hypervirial equation

• Published in: International journal of quantum chemistry Vol. 111; no. 5; pp. 937 - 949
• Main Authors: Alcoba, D. R., Tel, L. M., Pérez-Romero, E., Valdemoro, C.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.04.2011
• Subjects: contracted Schrödinger equation; correlation matrix; electronic correlation effects; G-matrix; hypervirial of the G-particle-hole matrix; reduced density matrix
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.22458

The G‐particle‐hole hypervirial (GHV) equation has been recently reported (Valdemoro et al., Sixth International Congress of the International Society for Theoretical Chemical Physics Vancouver: Canada, 2008. Alcoba et al., Int J Quantum Chem 2009, 109, 3178; Valdemoro et al., Int J Quantum Chem 2009, 109, 2622). This equation is the newest member of the family of equations which can be obtained by applying a matrix‐contracting mapping (Valdemoro, An R Soc Esp Fís 1983, 79, 106; Valdemoro, Phys Rev A 1985, 31, 2114; Valdemoro, in Density Matrices and Density Functionals, Reidel: Dordrecht, 1987; p 275.) to the matrix representation in the N‐electron space of the Schrödinger, Liouville and hypervirial equations. The procedure that we have applied in order to solve the GHV equation exploits the stationary property of the hypervirials (Hirschfelder, J Chem Phys 1960, 33, 1462; Hirschfelder and Epstein, Phys Rev 1961, 123, 1495) and follows the general lines of Mazziotti's variational approach for solving the anti‐Hermitian contracted Schrödinger equation (ACSE) (Mazziotti, Phys Rev Lett 2006, 97, 143002; Mazziotti, Phys Rev A 2007, 75, 022505; Mazziotti, J Chem Phys 2007, 126, 184101). In this article, we report how the method's convergence has been significantly enhanced and how its computational scaling has been considerably reduced (in both floating‐point operations and storage). The results for a variety of atomic and molecular calculations confirming these methodological improvements are reported here. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011