The multiconfiguration SCF method and large-scale configuration interaction in calculations for the A1 and B1 states of the water molecule

1987 ◽  
Vol 23 (1) ◽  
pp. 1-9 ◽  
Author(s):  
A. V. Luzanov ◽  
G. T. Klimko ◽  
A. L. Vul'fov
Keyword(s):  
Water Molecule ◽  
Configuration Interaction ◽  
Large Scale

scholarly journals Large-scale ab initio configuration interaction calculations for light nuclei

2012 ◽  
Vol 403 ◽  
pp. 012019 ◽  
Author(s):  
Pieter Maris ◽  
H Metin Aktulga ◽  
Mark A Caprio ◽  
Ümit V Çatalyürek ◽  
Esmond G Ng ◽  
...  
Keyword(s):  
Ab Initio ◽  
Configuration Interaction ◽  
Large Scale ◽  
Light Nuclei ◽  
Configuration Interaction Calculations

scholarly journals LARGE-SCALE FIRST PRINCIPLES CONFIGURATION INTERACTION CALCULATIONS OF OPTICAL ABSORPTION IN BORON CLUSTERS

Nano LIFE ◽  
2012 ◽  
Vol 02 (02) ◽  
pp. 1240004 ◽  
Author(s):  
RAVINDRA SHINDE ◽  
ALOK SHUKLA
Keyword(s):  
Optical Absorption ◽  
Absorption Spectra ◽  
Excited States ◽  
Configuration Interaction ◽  
Large Scale ◽  
Body Wave ◽  
Basis Sets ◽  
Linear Absorption ◽  
Transition Dipole ◽  
Boron Clusters

We have performed systematic large-scale all-electron correlated calculations on boron clusters B n(n = 2 - 5), to study their linear optical absorption spectra. Several possible isomers of each cluster were considered, and their geometries were optimized at the coupled-cluster singles doubles (CCSD) level of theory. Using the optimized ground-state geometries, the excited states of different clusters were computed using the multi-reference singles-doubles configuration–interaction (MRSDCI) approach, which includes electron correlation effects at a sophisticated level. These CI wave functions were used to compute the transition dipole matrix elements connecting the ground and various excited states of different clusters, eventually leading to their linear absorption spectra. The convergence of our results with respect to the basis sets, and the size of the CI expansion were carefully examined. The contribution of configurations to many body wave-function of various excited states suggests that the excitations involved are collective, plasmonic type.

Erzeugung und Untersuchung des Cyclopentadienons mit der Methode der temperaturabhängigen Photoelektronenspektroskopie / Preparation and Investigation of Cyclopentadienone by Variable Temperature Photoelectron Spectroscopy (VTPES)

1978 ◽  
Vol 33 (3) ◽  
pp. 383-385 ◽  
Author(s):  
Veit Eck ◽  
Günther Lauer ◽  
Armin Schweig ◽  
Walter Thiel ◽  
Hans Vermeer
Keyword(s):  
Dicarboxylic Acid ◽  
Gas Phase ◽  
Configuration Interaction ◽  
Photoelectron Spectroscopy ◽  
Large Scale ◽  
Variable Temperature ◽  
Acid Anhydride ◽  
Selection Procedures ◽  
Scale Perturbation ◽  
Configuration Interaction Calculations

AbstractUsing our VTPES technique cyclopentadienone is generated in the gas phase at 500-600 °C from the three different precursors cyclobutene-3,4-dicarboxylic acid anhydride, o-phenylene sulfite and o-benzoquinone and its PE spectrum is recorded. The PE spectrum and also the PE spectra of the various precursors as well as of the cyclopentadienone dimer are interpreted on the basis of our recently developed PERTCI method (i. e. performing large scale perturbation configuration interaction calculations in connection with selection procedures). The agreement between measured and calculated ionization potentials is good.

Large-scale CIV3 calculations of fine-structure energy levels and radiative rates in Al-like copper

2009 ◽  
Vol 87 (8) ◽  
pp. 895-907 ◽  
Author(s):  
G. P. Gupta ◽  
A. Z. Msezane
Keyword(s):  
Fine Structure ◽  
Configuration Interaction ◽  
Large Scale ◽  
Radiative Decay ◽  
Energy Levels ◽  
Decay Rates ◽  
Experimental Results ◽  
Oscillator Strengths ◽  
Correct Identification ◽  
Excitation Energies

We have performed large-scale CIV3 calculations of excitation energies from the ground state for 97 fine-structure levels as well as of oscillator strengths and radiative decay rates for all electric-dipole-allowed and intercombination transitions among the fine-structure levels of the terms belonging to the (1s22s22p6)3s23p, 3s3p2, 3s23d, 3p3, 3s3p3d, 3p23d, 3s3d2, 3s24s, 3s24p, 3s24d, 3s24f, and 3s3p4s configurations of Cu XVII. These states are represented by very extensive configuration-interaction (CI) wave functions obtained with the CIV3 (Configuration-Interaction Version 3) computer code of Hibbert. The important relativistic effects in intermediate coupling are incorporated by means of the Breit–Pauli Hamiltonian, which consists of the nonrelativistic term plus the one-body mass correction, Darwin term, and spin–orbit, spin–other-orbit, and spin–spin operators. To keep our calculated energy splittings as close as possible to the experimental values (wherever available), we have made small adjustments to the diagonal elements of the Hamiltonian matrices. Our calculated excitation energies, including their ordering, are in excellent agreement with the available experimental results. From our radiative decay rates we have also calculated radiative lifetimes of some fine-structure levels. The mixing among several fine-structure levels is found to be so strong that the correct identification of these levels becomes very difficult. We believe that our extensive calculations will be useful to experimentalists in identifying the fine-structure levels in their future work. In this calculation we also predict new data for several fine-structure levels where no other theoretical and (or) experimental results are available.

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