Theoretical study of lithium hydride (Li2H). 3. Approximate natural orbital contour diagrams and occupation numbers for the formation and dissociation of Li2H

1978 ◽  
Vol 100 (16) ◽  
pp. 4953-4961 ◽  
Author(s):  
Walter England ◽  
Nora H. Sabelli
Keyword(s):  
Theoretical Study ◽  
Lithium Hydride ◽  
Natural Orbital ◽  
Occupation Numbers ◽  
Approximate Natural Orbital

Theoretical study of the structure and stability of oligomers of lithium hydride

1981 ◽  
Vol 20 (11) ◽  
pp. 3659-3663 ◽  
Author(s):  
H. Kato ◽  
K. Hirao ◽  
K. Akagi
Keyword(s):  
Theoretical Study ◽  
Lithium Hydride ◽  
Structure And Stability

The Ground State Potential for the Chromium Dimer Revisited

2003 ◽  
Vol 68 (2) ◽  
pp. 265-274 ◽  
Author(s):  
Björn O. Roos
Keyword(s):  
Ground State ◽  
Theoretical Study ◽  
Relativistic Effects ◽  
Basis Set ◽  
Spectroscopic Constants ◽  
Natural Orbital ◽  
State Potential ◽  
Experimental Values ◽  
Atomic Natural Orbital ◽  
Caspt2 Calculations

Results are presented from a new theoretical study of the ground state potential curve of the chromium dimer using multiconfiguration second-order perturbation theory. A new basis set of the atomic natural orbital type is used where the construction includes correlation of the semi-core 3p orbitals and scalar relativistic effects are added using the Douglas-Kroll Hamiltonian. The active space used in the CASSCF/CASPT2 calculations comprised 16 orbitals with 12 active electrons. The resulting ground state potential is in agreement with experiment. Computed spectroscopic constants are (with experimental values within parentheses): Re = 1.66 (1.68) Å, D0 = 1.65 (1.53 ± 0.06) eV, ∆G1/2 = 413 (452) cm-1. Higher vibrational frequencies are also well reproduced.

scholarly journals Implications of pinned occupation numbers for natural orbital expansions. II: rigorous derivation and extension to non-fermionic systems

2020 ◽  
Vol 22 (2) ◽  
pp. 023002
Author(s):  
Tomasz Maciążek ◽  
Adam Sawicki ◽  
David Gross ◽  
Alexandre Lopes ◽  
Christian Schilling
Keyword(s):  
Rigorous Derivation ◽  
Natural Orbital ◽  
Occupation Numbers ◽  
Fermionic Systems

scholarly journals Implications of pinned occupation numbers for natural orbital expansions: I. Generalizing the concept of active spaces

2020 ◽  
Vol 22 (2) ◽  
pp. 023001
Author(s):  
Christian Schilling ◽  
Carlos L Benavides-Riveros ◽  
Alexandre Lopes ◽  
Tomasz Maciążek ◽  
Adam Sawicki
Keyword(s):  
Natural Orbital ◽  
Occupation Numbers
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