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Studies in the configuration interaction method. I. Combinatorial aspects of the downward‐robb algorithm
Author(s) -
Pauncz Ruben
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560200811
Subject(s) - unitary state , partition (number theory) , configuration interaction , algorithm , mathematics , recurrence relation , harmonic , computer science , combinatorics , physics , quantum mechanics , political science , law , excited state
The Downward‐Robb algorithm is one of the effective methods used in the unitary group approach to the configuration interaction treatment. The number of configurations corresponding to a given harmonic level (Paldus) or to a given total orbital weight (Downward‐Robb) can be determined by this algorithm. The knowledge of these numbers is essential for an effective implementation of the procedure. This article presents a new way to calculate these numbers. This procedure also yields novel relations among different partition functions.