Mean-Field Dynamics

The qc_lab.algorithms.MeanField class implements the mean-field (Ehrenfest) dynamics algorithm according to Tully 1998.

Settings

The mean-field algorithm has no default settings.

Initial State

The mean-field algorithm requires an initial diabatic wavefunction called wf_db which is a complex NumPy array with dimension sim.model.constants.num_quantum_states. For example:

sim.state.wf_db = np.array([1, 0], dtype=complex)

Output Variables

The following table lists the default output variables for the MeanField class.

MeanField Output Variables

Variable name	Description
classical_energy	Energy in the classical subsystem
quantum_energy	Energy in the quantum subsystem
dm_db	Diabatic density matrix

Example

The following example demonstrates how to run a mean-field simulation for a spin-boson model using all default settings.

import numpy as np
from qc_lab import Simulation # import simulation class
from qc_lab.models import SpinBoson # import model class
from qc_lab.algorithms import MeanField # import algorithm class
from qc_lab.dynamics import serial_driver # import dynamics driver

sim = Simulation()
sim.model = SpinBoson()
sim.algorithm = MeanField()
sim.state.wf_db= np.array([1, 0], dtype=complex)
data = serial_driver(sim)