PyCrystalField: Software for Calculation, Analysis, and Fitting of Crystal Electric Field Hamiltonians

TL;DR

PyCrystalField is a Python package that enables comprehensive calculation, analysis, and fitting of crystal electric field Hamiltonians for various ions, supporting ab initio calculations, symmetry analysis, and experimental data fitting.

Contribution

It introduces a versatile Python software that integrates ab initio calculations, symmetry analysis, and data fitting for crystal electric field Hamiltonians, enhancing research capabilities.

Findings

Supports ab initio CEF Hamiltonian calculations from point charge models

Performs symmetry analysis to identify nonzero parameters

Fits CEF models to experimental data

Abstract

We introduce PyCrystalField, a Python software package for calculating single-ion crystal electric field (CEF) Hamiltonians. This software can calculate a CEF Hamiltonian \textit{ab initio} from a point charge model for any transition or rare earth ion in either the $J$ basis or the $LS$ basis, perform symmetry analysis to identify nonzero CEF parameters, calculate the energy spectrum and observables such as neutron spectrum and magnetization, and fit CEF Hamiltonians to any experimental data. The theory, implementation, and examples of its use are discussed.