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MathGroup Archive 2007

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New release of package SNEG

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77452] New release of package SNEG
  • From: Rok Zitko <rok.zitko at ijs.si>
  • Date: Sat, 9 Jun 2007 05:30:48 -0400 (EDT)
  • Organization: Institut Jozef Stefan

A new version of the Mathematica package SNEG for performing
calculations using the operators of the second quantization formalism
of quantum mechanics has been released. In the past, SNEG has been
applied to perform exact diagonalizations on Hubbard clusters,
calculations of commutators of complex expressions, perturbation
theory and high-temperature expansions to higher orders, numerical
renormalization group (NRG) calculations, etc. This version adds the
following new functionality:

- support for bosonic operators,
- support for real (Majorana) fermionic operators,
- support for anti-commuting Grassman variables, Berezin integration,
  and fermionic coherent states,
- automatic simplifications of expressions with exponential functions of
  operators using Baker-Campbell-Hausdorff and Mendas-Milutinovic
  formulas,
- improved automatic canonical ordering of fermionic operators in
  the case of Fermi sea vacuum,
- improved handling of symbolic sums and automatic renaming of dummy
  indexes when name conflicts appear,
- built-in support for pretty printing of operator expressions,
  obviating the need to use the Notation package,
- code for rewriting creation operator expressions in terms of
  higher-level functions, such as number, hopping, spin, and 
  electron-electron repulsion terms,
- various performance improvements (for example, the generation of
  basis states with well-defined charge and spin quantum numbers is much
  faster).

Furthermore, the documentation has been significantly improved and is
now browsable in the Mathematica help system. The package is freely
(GPL license) available from

http://nrgljubljana.ijs.si/sneg


Kind regards,
Rok Zitko



Rok Zitko, rok.zitko at ijs.si
"Jozef Stefan" Institute
Ljubljana, Slovenia




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