Computational issues of configuration interaction frameworks describing open quantum systems

24th IUPAP Conference on Computational Physics

物理学;计算机科学

Michel, Nicolas^1

University of Tennessee, Michigan State University, United States^1

关键词: Closed quantum system;    Computational issues;    Computational technique;    Configuration interaction method;    Configuration interactions;    Density matrix renormalization group;    Long range asymptotic behavior;    Open quantum systems;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/454/1/012065/pdf
DOI  :  10.1088/1742-6596/454/1/012065

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

Open quantum systems (OQS), extended in space (halo nuclei) or even unbound, differ from closed quantum systems (CQS), for which the methods of standard shell model (SM) [1] can be utilized in order to expand their wave function in a configuration interaction framework. Configuration interaction methods based on the use of Berggren bases [2], comprising bound, resonant and scattering states, which have the ability to generate the very long range asymptotic behavior of OQSs, are used instead for that matter. This demands the introduction of new computational techniques, including the optimization and discretization of the Berggren basis [3], the development of an algorithm to efficiently calculate their two-body matrix elements [4], and an overall optimization of memory storage absent from SM, where, for instance, all data related to proton and neutron spaces only can be precalculated and stored [1]. In order to diagonalize the very large induced matrices, the Density Matrix Renormalization Group (DMRG) method [5] extended to OQSs has been developed [6, 7]. A renormalization procedure which generates more and more correlated many-body basis states iteratively is used therein, so that the Hamiltonian matrix to diagonalize is very small compared to that occurring with a many-body basis of independent particles [6, 7]. Parallelization of presented methods will also be discussed.