Controlling the N- and S-representability of the second-order reduced density matrix: The doublet-state case
نویسندگان
چکیده
D. R. Alcoba, C. Valdemoro, L. M. Tel, and E. Pérez-Romero Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 1428 Buenos Aires, Argentina Instituto de Matemáticas y Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain Departamento de Química Física, Facultad de Ciencias, Universidad de Salamanca, 3708 Salamanca, Spain Received 22 November 2007; revised manuscript received 13 February 2008; published 17 April 2008
منابع مشابه
Concepts and Experiences of Density Matrix Optimalization
The second-order reduced density matrix is a basic tool for describing quantum mechanical systems. In addition to its numerous advantage, we meet a basic difficulty when using density matrix. Because of the so-called N-representability problem the free variation of it is not possible in quantum mechanical calculation. In this study the problem is sketched, and recent results are overwiewed. In ...
متن کاملUniqueness of the solution of the contracted Schrödinger equation
In this paper two fundamental questions in the contracted Schrödinger equation ~CSE! approach are considered by using Lipkin’s quasispin model: 1-1 mapping between the second-order reduced density matrix ~2-RDM! and the wave function of an excited state, and the uniqueness of the solution of CSE under incomplete N-representability conditions. We present some examples of the wave functions that ...
متن کاملAn Improved ISM Equation of State for Polar Fluids
We developed an equation of state (EOS) by Ihm, Song, and Mason (ISM) for polar fluids. The model consists of four parameters, namely, the second virial coefficient, an effective van der Waals co-volume, a scaling factor, and the reduced dipole moment. The second virial coefficient is calculated from a correlation that uses the heat of vaporization, and the liquid density at the normal boiling ...
متن کاملN-representability problem within the framework of the contracted Schrödinger equation
A a procedure is proposed by which, in the course of an iterative solution of the second-order contracted Schrödinger equation, The N representability of the second-order reduced density matrix can be tested with increasing stringency. This procedure was suggested by an extended study of the G conditions and from the contraction into the two-electron space of an N-fermion relation, expressing i...
متن کاملActive-space N-representability constraints for variational two-particle reduced density matrix calculations.
The ground-state energy of a system of fermions can be calculated by minimizing a linear functional of the two-particle reduced density matrix (2-RDM) if an accurate set of N-representability conditions is applied. In this Letter we introduce a class of linear N-representability conditions based on exact calculations on a reduced active space. Unlike wave-function-based approaches, the 2-RDM me...
متن کامل