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Imposing bounds on the high‐order reduced density matrices elements
Author(s) -
Valdemoro C.,
Alcoba D. R.,
Tel L. M.,
PérezRomero E.
Publication year - 2001
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.1517
Subject(s) - density matrix , order (exchange) , matrix (chemical analysis) , mathematics , quantum , third order , computational chemistry , pure mathematics , mathematical physics , combinatorics , chemistry , quantum mechanics , physics , philosophy , theology , finance , chromatography , economics
A family of N ‐representability conditions are imposed on the third‐ and fourth‐order reduced density matrix elements in order to ascertain that they are within bounds. These bounds are needed in the construction of high‐order reduced density matrices as well as in the correction of the matrices which result from the iterative solution of the standard and of the modified contracted Schrödinger equations. The results obtained for the fourth‐order reduced density matrix are strikingly good in two nontrivial cases. A new and more economical method for constructing the fourth‐order reduced density matrix in terms of the lower order ones is also reported here. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001