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