Ground state and vertical excitation energies of the diazene isomers with the coupled cluster method

2008 ◽  
Vol 108 (12) ◽  
pp. 2108-2116 ◽  
Author(s):  
Katarzyna Szopa ◽  
Monika Musiał ◽  
Stanisław A. Kucharski
Keyword(s):  
Ground State ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Excitation Energies ◽  
Vertical Excitation ◽  
Vertical Excitation Energies

The Fock-Space Coupled-Cluster Method in the Calculation of Excited State Properties

2005 ◽  
Vol 70 (6) ◽  
pp. 811-825 ◽  
Author(s):  
Monika Musiał ◽  
Leszek Meissner
Keyword(s):  
Experimental Data ◽  
Excited States ◽  
Fock Space ◽  
Hamiltonian Formulation ◽  
Basis Sets ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Coupled Cluster Method ◽  
Excitation Energies ◽  
Equilibrium Geometries

Our recently developed intermediate Hamiltonian Fock-space coupled-cluster (FS-CC) method with singles and doubles is applied to calculation of equilibrium geometries, harmonic frequencies and adiabatic excitation energies for some excited states of N2 and CO. Due to the intermediate Hamiltonian formulation, which provides a robust computational scheme for solving the FS-CC equations, and the efficient factorization strategy, relatively large basis sets and reference spaces are employed permitting a comparison of calculated properties with experimental data.

QCD GLUEBALLS WITHIN A COUPLED CLUSTER APPROACH

2001 ◽  
Vol 15 (10n11) ◽  
pp. 1732-1735 ◽  
Author(s):  
D. SCHÜTTE ◽  
A. WICHMANN ◽  
V. WETHKAMP
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Ground State ◽  
Cluster Method ◽  
Coupled Cluster ◽  
Gauge Field Theory ◽  
Coupled Cluster Method ◽  
Cluster Approach ◽  
Monte Carlo Techniques ◽  
Lattice Gauge

The validity of the coupled cluster method is studied within the lattice gauge field theory given by a SU(2) pure glue theory in 2+1 dimensions. Satisfactory convergence is observed for the ground state, but the method is less successful for the prediction of glueballs. We propose to improve the coupled cluster method for excited state by combining it with standard Monte-Carlo techniques which potentially cure the non-hermiticity problems caused by the truncation.

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