rd.quaternion_covariance_matrix()

RotationalDiffusion.models.quaternion_covariance_matrix(lag_times, diffusion_coeffs, principal_axes=array([[1., 0., 0.], [0., 1., 0.], [0., 0., 1.]]))

\(3 imes 3`(sub-)quaternion covariance matrix of an ideal Brownian rotor with diffusion tensor :math:`D\).

Utilizes Equations 2-4 from Favro (1960) as described by Linke et al. (2017).

Parameters:

lag_times: (N,) ndarray°

Discrete lag times at which to compute the quaternion covariance matrix.

diffusion_coeffs: (3,) ndarray

Diffusion coefficients.

Returns:

Q: (N, 3, 3) ndarray

Quaternion covariance matrix of D.