Overview

PointGroupNRG is a Julia package designed to perform Numerical Renormalization Group calculations for magnetic impurity Anderson Hamiltonians with several charge, orbital and spin symmetries, including finite point and double group symmetries. A comprehensive user's manual can be found in manual/. The presentation of the code and a comprehensive exposition of the implemented procedure can be found in this paper and this paper.

Compatibility

• Tested and working for Julia 1.10.0
• Issues have been found in Julia 1.8.x

Changes

Specific stable versions vX.Y.Z of the code are contained in branches. The master branch contains the latest changes.

v1.0.0 (1/7/2024)

• Working version with the functionality described in this paper

master (1/7/2024)

• Double group symmetries and total angular momentum conservation available.
• Modified documentation:
  • doc/Manual.md replaced by manual/manual.pdf.
  • doc/Tutorial.md removed.
• Interface changed, see manual/manual.pdf.
• New examples in examples/.
• Precompilation scripts in precompile/ removed.
• Incompatible with v1.0.0.

v2.0.0 (4/8/2024):

• Stable version with functionality introduced in 1/7/2024.

Installation

PointGroupNRG is not in the General Registry. To use it from your own Julia environment, download or clone PointGroupNRG and add it to your project:

pkg> activate <path_to_project> 
pkg> add <path_to_PointGroupNRG>

The pkg> mode is entered by typing ] in the julia> shell. If a new version is pulled from GitHub, for the changes to apply it is necessary to update the added PointGroupNRG package in the local project using

pkg> up

Instead of adding the package from a local project, the downloaded/cloned repository can be activated and instantiated:

pkg> activate <path_to_PointGroupNRG>
pkg> instantiate # only the first time

Examples

Examples for several systems are provided in the examples/ directory. To run them, go to the corresponding directory, e.g. examples/krishnamurthy1980, and run the scripts:

$ cd <...>/PointGroupNRG&/examples/krishnamurthy1980
$ ./multiplets.jl

This computes the multiplet states to be used in the NRG calculation. Afterwards, edit the nrg.jl script to set the variable run to the desired value, perform any other modifications, and run the script:

$ julia
julia> include("nrg.jl")

Loading the script within a Julia session allows to skip package loading time for subsequent runs. Check the output in the generated directories (see manual/manual.pdf).

Precompilation

To avoid the package loading latency, it is possible to create a sysimage using the PackageCompiler package. See the PackageCompiler.jl documentation and, in particular, the sysimage section.