Results 321 to 330 of about 12,410,821 (356)

All harmonic 2-spheres in the unitary group, completely explicitly

, 2008
We give a completely explicit formula for all harmonic maps of finite uniton number from a Riemann surface to the unitary group U(n) in any dimension, and so all harmonic maps from the 2-sphere, in terms of freely chosen meromorphic functions on the ...
M. J. Ferreira, B. Simões, J. Wood
semanticscholar   +1 more source

The unitary group formulation of the N‐ particle problem

, 2009
The representation of an N-particle Hamiltonian on an Nth rank orbital product space is exactly modeled by a second-degree polynomial in the infinitesimal generators of the unitary group.
Frederick Albert Matsen IV
semanticscholar   +1 more source

Application of unitary group methods to configuration interaction calculations

, 1979
A computational approach to the direct configuration interaction method is described. The method is formulated using the calculus of the generators of the unitary group.
D. Hegarty, M. Robb
semanticscholar   +1 more source

Generalizations of the direct CI method based on the graphical unitary group approach. I. Single replacements from a complete CI root function of any spin, first order wave functions

, 1979
The direct CI method is generalized to the class of wave functions, denoted as first order wave functions. With a first order wave function is meant a complete CI expansion in a small internal valence space and single excitations outside this space.
P. Siegbahn
semanticscholar   +1 more source

On the Representations of the Semisimple Lie Groups. I. The Explicit Construction of Invariants for the Unimodular Unitary Group in N Dimensions

, 1963
It is intended in the present series of papers to discuss explicit constructive determinations of the representations of the semisimple Lie groups SUn by an extension of the Racah‐Wigner techniques developed for the two‐dimensional unimodular unitary ...
L. Biedenharn
semanticscholar   +1 more source

Generalizations of the direct CI method based on the graphical unitary group approach. II. Single and double replacements from any set of reference configurations

, 1980
The direct CI method is generalized to the case of all single and double replacements from an arbitrary set of reference configurations. This is a continuation of the work and ideas presented in an earlier paper on first order wave functions.
P. Siegbahn
semanticscholar   +1 more source

The Loop-Driven Graphical Unitary Group Approach: A Powerful Method for the Variational Description of Electron Correlation

, 1980
The graphical unitary group approach (UGA) has been cast into an extraordinarily powerful form by restructuring the Hamiltonian in terms of loop types. This allows the adoption of the loop-driven formulation which illuminates vast numbers of previously ...
B. Brooks, W. D. Laidig, Paul Saxe, N. Handy, H. Schaefer   +4 more
semanticscholar   +1 more source

The graphical unitary group approach to the electron correlation problem. Methods and preliminary applications

, 1979
Recent theoretical research by Paldus and by Shavitt has strongly suggested that the unitary group approach to the many body problem may be useful in molecular electronic problems.
B. Brooks, H. Schaefer
semanticscholar   +1 more source

Clifford algebra unitary group approach to many‐electron correlation problem

, 1985
Unitary group approach (UGA) to the many‐electron correlation problem is generalized by embedding the unitary group U(n) in a much larger group U(2n) via the rotation groups SO(m) with m=2n or 2n+1 and their covering group Spin (m).
J. Paldus, C. R. Sarma
semanticscholar   +1 more source

Emergent Behavior of a Second-Order Lohe Matrix Model on the Unitary Group

Journal of statistical physics, 2019
Seung‐Yeal Ha, Doheon Kim
semanticscholar   +1 more source