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Variational localized‐site cluster expansions. VII. Higher ansätze and the linear heisenberg model
Author(s) -
Garcíaabach M. A.,
Klein D. J.
Publication year - 1977
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.560120205
Subject(s) - cluster expansion , cluster (spacecraft) , heisenberg model , k nearest neighbors algorithm , yield (engineering) , coupled cluster , physics , mathematics , statistical physics , mathematical physics , quantum mechanics , molecule , computer science , thermodynamics , ferromagnetism , artificial intelligence , programming language
The localized‐site cluster expansion technique is applied to the infinite linear Heisenberg model with both nearest‐neighbor and next nearest‐neighbor interactions. These cluster ansätze are systematically studied and improved, up to the so‐called 5‐site approximation. Generally we find the present cluster ansätze yield the most accurate variational results yet available.