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Showing 1 to 20 of 90 for “"Density Matrix"”.
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Helicity density matrix formalism and polarized processes in QCD
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.
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Conjugate gradient density matrix search: A linear scaling alternative to diagonalization
… contributions to Gaussian-based Hartree-Fock and density functional theory Hamiltonians have demonstrated near-linear scaling with molecular size for these steps. These advances leave the ${\cal O}(N\sp3)$ diagonalization bottleneck as the rate determining step for very large systems. In this …
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Density Matrix Renormalization Group Studies of Strongly Correlated Systems in Low Dimensions
The density matrix renormalization group method (DMRG) is a powerful numerical method for strongly correlated systems, which often cannot be solved analytically either by the mean field approach or through perturbation. The DMRG is originally proposed as an iterative search of the ground state in …
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Longitudinal atom optics : measuring the density matrix of a matter wave beam
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1999.
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A Study of Omega-Zero Spin-Density Matrix Elements in the Reaction Negative Pion-Proton Going to Neutral Omega-Resonance Neutron at 3.65, 4.5, and 5.5 Gev/c
Made available in DSpace on 2015-05-12T22:38:45Z (GMT). No. of bitstreams: 2 license.txt: 4848 bytes, checksum: 96035ab3f5e1c23cc7138a224ce498bd (MD5) 7207041.PDF: 1973655 bytes, checksum: 8e97fccaee54eca5d59800e73da23f41 (MD5) Previous issue date: 1971
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A Study of the Omega-Zero Spin-Density Matrix Elements in the Reaction Pi-Minus Proton Goes to Omega-Zero Neutron at 3.65, 4.5, and 5.5 GeV/c
A study was made of the WO spin-density matrix elements in the o reaction TI p~ n. The data were collected using a combination of scintillation counters and optical spark chambers designed to detect events of the type + TI p-TI TI yyn. Incident pions of momenta 3.65, 4.5, and 5.5 GeV/c were …
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A Study of the Omega-Zero Spin-Density Matrix Elements in the Reaction Pi-Minus Proton Goes to Omega-Zero Neutron at 3.65, 4.5, and 5.5 GeV/c
Submitted by Rachelle Ramer (rramer2@illinois.edu) on 2012-01-20T23:24:32Z No. of bitstreams: 1 1971_rosenberg.pdf: 2216476 bytes, checksum: aac4bf990c58ba48d8a149f866279450 (MD5)
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N-Representability in the Quantum Kernel Energy Method
… been generalized to provide the one-body density matrix for the full molecule. This generalization greatly expands the utility of the method since the density matrix enables simple calculation of the expectation value of any observable associated with a one-body operator. More importantly, …
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Experimental Correlation and Self Consistent Analysis of an Infrared, Fir, Mw Triple Resonant System in Amonnia
… the IR, FIR, and MW were studied by means of density matrix. The FIR and MW frequencies calculated from the self consistent analysis have been verified by the experiments. The measurements for the MW pressure dependence were justified by the density matrix calculations.
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New ab initio formulation of electron correlation and spin resonance
… feasible approximations of the two-body density matrix as a finite sum of tensor products of single-particle operators. Representing correlations by a single tensor product leads to the recently proposed "natural orbital functional." We show that this theory is no more accurate than …
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Carrier excitations and nonlinear optical effects in semiconductor quantum wells
Density matrix formulation is used to investigate the nonlinear optical properties of semiconductor quantum-well devices. The generation of terahertz electromagnetic pulses from ultrafast optical pulse excitations of semiconductor heterostructures is studied in the time domain with a three-level …
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Quantum-classical and semiclassical path integral methods for condensed phase dynamics
… dynamics of the system is often described by the density matrix. Path integral formulation of the density matrix provides a versatile tool for studying quantum dynamics in condensed phase. Unlike the Schro ̈dinger equation in which the wavefunction is central, Feynman’s path integral formulation …
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Quantum dynamical study of Si(100) surface-mounted, STM-driven switches at the atomic and molecular scale
… dynamics are provided by the propagation of the density matrix in time via an according set of equations of motion (EQM). The latter are based on the open-system density matrix theory in Lindblad form. First order perturbation theory is used to evaluate those transition rates between vibrational …
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Dynamics of a four-well system interacting with a dissipative environment
… Also in this limit, the time evolution of the density matrix of a four-well system is found. The diagonals elements are then rederived by considering an infinite chain of wells.
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Quantum information and thermodynamics of general relativity
… derive the evolution equations for the reduced density matrix of the detector, invoking neither the Markov approximation nor the Rotating Wave Approximation (RWA). We find that at early times and in the regime of small accelerations, the non-Markovian effects are particularly pronounced, …
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Scaling of entanglement entropy in some condensed matter systems
… parts. Chapter 2 studies the thermal reduced density matrices in fermion and spin systems on ladders. Chapter 3 studies the many-body localization phase transition in a Rokhsar-Kivelson type wave function. Chapter 4 studies the subleading correction term of entanglement entropy in 2+1 …
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A-2 meson production in pi-minus proton interactions at five BeV
… p!s from the A2 decay. A calculation of the spin-density matrix elements, assuming a JF= 2+ assignment for the A2, yields results consistent with resonance production via p meson exchange. The values for the density matrix elements are also in.general agreement with those computed from the npi …
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Spin Polarization of Ground State Electron Gas at Low Densities
… To construct a high quality wavefunction or density matrix at zero and finite temperature, we apply the Variational Density Matrix method. We use Random Phase Approximation to derive two-body Jastrow correlation functions. We also include backflow and threebody correlations in the …
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Development of large scale tight-binding methods, and application to electron transfer in symmetric dielectric barrier discharges (DBDS)
… structure theory. In tight-binding and density functional theory, the most expensive part of the computation is obtaining the density matrix, which traditionally scales cubically with the number of atoms. Tight-binding is a semi-empirical electronic structure method that is the least …
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Linear scaling density functional theory with Gaussian orbitals and periodic boundary conditions
… and computational details of our Kohn-Sham density functional method with Gaussian orbitals for systems with periodic boundary conditions (PBC). When solving iterative self-consistent field (SCF) equations of density functional theory (DFT), the most computationally demanding tasks are …
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