Combinatorial level densities by the real-time method

Levels densities of independent-particle fermionic systems can be calculated easily by using the real-time representation of the evolution operator together with the fast Fourier transform. We describe the method and implement it with a set of Python programs. Examples are provided for the total and partial levels densities of a heavy deformed nucleus (164Dy). The partial level densities that may be calculated are the projected ones on neutron number, proton number, azimuthal angular momentum, and parity.Program summaryProgram title: rt_levels.pyCatalog identifier: AEUI_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEUI_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 6515No. of bytes in distributed program, including test data, etc.: 263821Distribution format: tar.gzProgramming language: Python.Computer: PCs.Operating system: Unix, Apple OSX.RAM: 1 MBClassification: 17.16.External routines: NumpyNature of problem: Compute many-body level densities of finite systems of fermions described by their single-particle spectraSolution method: Fast Fourier transform of the real-time Green’s functionRunning time: A few minutes to one hour