IBAR: Interacting boson model calculations for large system sizes

Abstract

Scaling the system size of the interacting boson model-1 (IBM-1) into the realm of hundreds of bosons has many interesting applications in the field of nuclear structure, most notably quantum phase transitions in nuclei. We introduce IBAR, a new software package for calculating the eigenvalues and eigenvectors of the IBM-1 Hamiltonian, for large numbers of bosons. Energies and wavefunctions of the nuclear states, as well as transition strengths between them, are calculated using these values. Numerical errors in the recursive calculation of reduced matrix elements of the d-boson creation operator are reduced by using an arbitrary precision mathematical library. This software has been tested for up to 1000 bosons using comparisons to analytic expressions. Comparisons have also been made to the code PHINT for smaller system sizes. Program summaryProgram title: IBARCatalogue identifier: AELI_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELI_v1_0.htmlProgram obtainable from: CPC Program Library, Queenʼs University, Belfast, N. IrelandLicensing provisions: GNU General Public License version 3No. of lines in distributed program, including test data, etc.: 28 734No. of bytes in distributed program, including test data, etc.: 4 104 467Distribution format: tar.gzProgramming language: C++Computer: Any computer system with a C++ compilerOperating system: Tested under LinuxRAM: 150 MB for 1000 boson calculations with angular momenta of up to L=4Classification: 17.18, 17.20External routines: ARPACK (http://www.caam.rice.edu/software/ARPACK/)Nature of problem: Construction and diagonalization of large Hamiltonian matrices, using reduced matrix elements of the d-boson creation operator.Solution method: Reduced matrix elements of the d-boson creation operator have been stored in data files at machine precision, after being recursively calculated with higher than machine precision. The Hamiltonian matrix is calculated and diagonalized, and the requested transition strengths are calculated using the eigenvectors.Restrictions: The 1000 boson coefficients for L=0 and L=20 have been included in the IBAR distribution and the 7.3 GB of data that make up the remaining coefficients for L=21 to L=2000 are available upon request.Running time: If the provided example is changed to include 100 bosons, the calculation requires about 1 second of run time. For 1000 bosons, the calculation requires about 9 minutes of run time.