DiPolMol-Py

A Python package to calculate the rotational and hyperfine structure of doublet-Sigma molecules (e.g., CaF, BaF, SrF) in the presence of external fields.

DiPolMol-Py is licensed under a BSD 3 clause license, a copy can be found here <LICENSE>_.

If you use our work for academic purposes you can cite us using:

B.Humphreys et al. DiPolMol-Py: A Python package for calculations for $^{2}{\Sigma}$ ground-state molecules (https://arxiv.org/pdf/2503.21663).

Installation

All .py files can be downloaded from the github repository (durham-qlm/DiPolMol).

The repository contains a folder Programme Files which includes the main notebooks required to run the programme. There is also a folder Examples consisting of various examples of how to calculate different effects.

To run the code, all Programme Files must be downloaded and saved, the user can then either copy the example files into the same folder and run them directly or write their own code, saved in the same folder, and importing the Programme files.

Package structure

Programme Files:

Hamiltonian – used to build the required Hamiltonian using matrix representation, including the field-free Hamiltonian and in the presence of magnetic, dc electric and off-resonant light fields.

Calculate – uses the eigenstates and eigenenergies found from diagonalising the Hamiltonian to run various calculations. Can be used to identify quantum numbers of eigenstates, calculate transition dipole moments and polarisabilities.

Constants – includes all known constants for CaF, BaF and SrF.

Examples:

There are three example files for calculating the energy structure in the presence of a magnetic, off-resonant light and electric field (example_Bfield, example_ac_Efield, example_dc_Efield).

There are two files to calculate the electric and magnetic moments of states (example_electric_moment, example_magnetic_moment).

We provide example_polarisability to calculate the polarisability for a given wavelength and polarisation of light.

Finally, example_tdm can be used to calculate the transition dipole moment.

Example

.. code-block:: python

import numpy as np
import hamiltonian as hamiltonian
import calculate as calc
from constants import SrF

Nmax=4 #Identify the maximum N 
H0,H_B,H_dc,H_ac 
	= hamiltonian.build
		(Nmax,SrF,zeeman=True,Edc=False
          ,Eac=False) 

B = np.linspace(0,100,5000)*1e-4 #Tesla

H = H_0[..., None] + H_B[..., None]*B
H = H.transpose(2,0,1)

energies, states, label_list = 
   calc.solve(H, Nmax, SrF,label=True, B)

Resulting plot of above code

.. image:: Images/zeeman_SrF_plot.png :width: 400 :alt: Resulting plot of above example

For more examples of usage, see the ./Examples folder.