Density matrix ground state

DensilysCurrent Specifies that population analysis procedures use the excited state density matrix rather than the ground state SCF density. 

In the electronic ground state, the six rr-electrons occupy the three lowest-energy orbitals (the first three from Table 7.2). The Huckel rr-electron charge density matrix is... 

The main output is shown in Figure 11.16. The energy of the ground state is given, together with the one-electron symbolic density matrix . 

Time-dependent response theory concerns the response of a system initially in a stationary state, generally taken to be the ground state, to a perturbation turned on slowly, beginning some time in the distant past. The assumption that the perturbation is turned on slowly, i.e. the adiabatic approximation, enables us to consider the perturbation to be of first order. In TD-DFT the density response dp, i.e. the density change which results from the perturbation dveff, enables direct determination of the excitation energies as the poles of the response function dP (the linear response of the KS density matrix in the basis of the unperturbed molecular orbitals) without formally having to calculate a(co). 

Since the phenoxyls possess an S = ground state, they have been carefully studied by electron paramagnetic spectroscopy (EPR) and related techniques such as electron nuclear double resonance (ENDOR), and electron spin-echo envelope modulation (ESEEM). These powerful and very sensitive techniques are ideally suited to study the occurrence of tyrosyl radicals in a protein matrix (1, 27-30). Careful analysis of the experimental data (hyperfine coupling constants) provides experimental spin densities at a high level of precision and, in addition, the positions of these tyrosyls relative to other neighboring groups in the protein matrix. 

The purpose of spin-polarized DFT is again to describe the system (molecule, cluster,...) with an auxiliary noninteracting system of one-particle spinors xJ/j,. ..,v]/N. The ground state density matrix of this noninteracting system... 

M. Rosina, A lower bound on the ground state energy of some few-nucleon systems, in Report of the Density Matrix Seminar (A. J. Coleman and R. M. Erdahl, eds.), Queen s Press, Kingston, Ontario, 1969, p. 82. 

M. V. Mihailovic and M. Rosina, The particle-hole states in some light nuclei calculated with the two-body density matrix of the ground state. Nucl. Phys. A237, 229-234 (1975). 

M. Rosina and M. V. Mihailovic, The determination of the particle—hole excited states by using the variational approach to the ground state two-body density matrix, in International Conference on Properties of Nuclear States, Montreal 1969, Les Presses de I Universite de Montreal, 1969. 

In 1927 Landau [I] and von Neumann [2] introduced the density matrix into quantum mechanics. The density matrix for the A-electron ground-state... 

Both the energy as well as the one- and two-electron properties of an atom or molecule can be computed from a knowledge of the 2-RDM. To perform a variational optimization of the ground-state energy, we must constrain the 2-RDM to derive from integrating an A -electron density matrix. These necessary yet sufficient constraints are known as A -representability conditions. 

D. A. Mazziotti, Variational minimization of atomic and molecular ground-state energies via the two-particle reduced density matrix. Phys. Rev. A 65, 062511 (2002). 

M. Rosina, Application of 2-body density matrix of ground-state for calculations of some excited-states. hit. J. Quantum Chem. 13, 737 (1978). 

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