How to Use Molecule Class

The Molecule class represents a single quantum-mechanical molecule with a set of electronic energy levels. The examples below show the most common operations.

Creating a molecule

Provide a list of electronic energies (in internal units, or inside a with qr.energy_units(...) block) and retrieve the Hamiltonian:

import quantarhei as qr

# electronic energies: ground state at 0, excited state at 1 (internal units)
en = [0.0, 1.0]
m = qr.Molecule(elenergies=en)

H = m.get_Hamiltonian()
print(H)

Setting a transition dipole moment

Use set_dipole to assign the transition dipole moment between two states:

import quantarhei as qr

en = [0.0, 1.0]
m = qr.Molecule(elenergies=en)

# set the 0->1 transition dipole along the x-axis
m.set_dipole(0, 1, [1.0, 0.0, 0.0])

Adding a vibrational mode

Intramolecular vibrational modes are added with Mode and add_Mode:

import quantarhei as qr

en = [0.0, 1.0]
m = qr.Molecule(elenergies=en)

# create a mode with frequency 0.01 (internal units)
mod = qr.Mode(frequency=0.01)
m.add_Mode(mod)