Density matrix method chemical

Kharkats, Y.L, Madumarov, A.K., and Vorotyntsev, M.A. (1974) Application of density matrix method in quantum-mechanical calculation of bridge-assisted electron-transfer probability in polar media. Journal of the Chemical Society. Faraday Transactions II, 70, 1578-1590. 

Pump-probe experiment is an efficient approach to detect the ultrafast processes of molecules, clusters, and dense media. The dynamics of population and coherence of the system can be theoretically described using density matrix method. In this chapter, for ultrafast processes, we choose to investigate the effect of conical intersection (Cl) on internal conversion (IC) and the theory and numerical calculations of intramolecular vibrational relaxation (IVR). Since the 1970s, the theories of vibrational relaxation have been widely studied [1-7], Until recently, the quantum chemical calculations of anharmonic coefficients of potential-energy surfaces (PESs) have become available [8-10]. In this chapter, we shall use the water dimer (H20)2 and aniline as examples to demonstrate how to apply the adiabatic approximation to calculate the rates of vibrational relaxation. 

Sand, A. M., Schwerdtfeger, C. A., Mazziotti, D. A. (2012). Strongly correlated barriers to rotation from parametric two-electron reduced-density-matrix methods in application to the isomerization of diazene. The Journal of Chemical Physics, 136, 034112. 

Concluding this brief survey, we may note that most of the papers on this aspect of chemical kinetics derive from the further development of the theory of radiational and radiationless transitions. The most general approach is the density matrix method developed in recent years which is a generalization of the method of Kubo and Toyozawa. ... 

Carbon Composites. In this class of materials, carbon or graphite fibers are embedded in a carbon or graphite matrix. The matrix can be formed by two methods chemical vapor deposition (CVD) and coking. In the case of chemical vapor deposition (see Film deposition techniques) a hydrocarbon gas is introduced into a reaction chamber in which carbon formed from the decomposition of the gas condenses on the surface of carbon fibers. An alternative method is to mold a carbon fiber—resin mixture into shape and coke the resin precursor at high temperatures and then foUow with CVD. In both methods the process has to be repeated until a desired density is obtained. 

M. Rosina, (a) Direct variational calculation of the two-body density matrix (b) On the unique representation of the two-body density matrices corresponding to the AGP wave function (c) The characterization of the exposed points of a convex set bounded by matrix nonnegativity conditions (d) Hermitian operator method for calculations within the particle-hole space in Reduced Density Operators with Applications to Physical and Chemical Systems—II (R. M. Erdahl, ed.), Queen s Papers in Pure and Applied Mathematics No. 40, Queen s University, Kingston, Ontario, 1974, (a) p. 40, (b) p. 50, (c) p. 57, (d) p. 126. 

This volume in Advances in Chemical Physics provides a broad yet detailed survey of the recent advances and applications of reduced-density-matrix mechanics in chemistry and physics. With advances in theory and optimization, Coulson s challenge for the direct calculation of the 2-RDM has been answered. While significant progress has been made, as evident from the many contributions to this book, there remain many open questions and exciting opportunities for further development of 2-RDM methods and applications. It is the hope of the editor and the contributors that this book will serve as a guide for many further advenmres and advancements in RDM mechanics. 

The ADMA and SADMA methods generate ab initio quality density matrices P for large molecules M, while avoiding the computation of macromolecular wave functions. At the Hartree-Fock level, the first-order density matrix P fully determines all higher-order density matrices. Within the Hartree-Fock framework, expectation values for one-electron and two-electron operators can be computed using the first-order and second-order density matrices. Consequently, the ADMA and SADMA methods provide new possibilities for adapting quantum-chemical techniques for macromolecules. 

Specific aspects of the quantum chemical concept of local electron densities and functional groups of chemistry have been discussed, with emphasis on the Additive Fuzzy Density Fragmentation (AFDF) Principle, on the Adjustable Density Matrix Assembler (ADMA) Method of using a local density matrix formalism of fuzzy electron density fragments in macromolecular quantum chemistry, and on the fundamental roles of the holographic electron density theorem, local symmetry, and symmetry deficiency. 

The same Mulliken-Mezey method, and the more elaborate alternative partitioning schemes serve as the basis of the ALDA (adjustable local density assembler) method and the ADMA (adjustable density matrix assembler) technique. The ALDA and ADMA methods generate geometry-adjustable electronic densities and macromolecular density matrices. The ADMA macromolecular density matrices can be computed without determining a macromolecular wave function, a feature advantageous in the macromolecular application of a variety of quantum-chemical... 

Roos B O, P R Taylor and E M Siegbahm 1980 A Complete Active Space SCF Method (CASSCF) Using a Density Matrix Formulated Super-CI Approach Chemical Physics 48 157-173. 

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