Subsections
frame_order.select_model
Select and set up the Frame Order model.
frame_order.select_model(model=None)
model: The name of the preset Frame Order model.
Prior to optimisation, the Frame Order model should be selected. These models consist of three parameter categories:
The average domain position. This includes the parameters ave_pos_alpha, ave_pos_beta, and ave_pos_gamma. These Euler angles rotate the tensors from the arbitrary PDB frame of the moving domain to the average domain position.

The frame order eigenframe. This includes the parameters eigen_alpha, eigen_beta, and eigen_gamma. These Euler angles define the major modes of motion. The cone central axis is defined as the zaxis. The pseudoelliptic cone x and yaxes are defined as the x and yaxes of the eigenframe.

The cone parameters. These are defined as the tilttorsion angles cone_theta_x, cone_theta_y, and cone_sigma_max. The cone_theta_x and cone_theta_y parameters define the two cone opening angles of the pseudoellipse. The amount of domain torsion is defined as the average domain position, plus and minus cone_sigma_max. The isotropic cones are defined by setting cone_theta_x = cone_theta_y and converting the single parameter into a 2
^{nd} rank order parameter.

The list of available models are:
 `pseudoellipse' 
 The pseudoelliptic cone model. This is the full model consisting of the parameters ave_pos_alpha, ave_pos_beta, ave_pos_gamma, eigen_alpha, eigen_beta, eigen_gamma, cone_theta_x, cone_theta_y, and cone_sigma_max.
 `pseudoellipse, torsionless' 
 The pseudoelliptic cone with the torsion angle cone_sigma_max set to zero.
 `pseudoellipse, free rotor' 
 The pseudoelliptic cone with no torsion angle restriction.
 `iso cone' 
 The isotropic cone model. The cone is defined by a single order parameter s1 which is related to the single cone opening angle cone_theta_x = cone_theta_y. Due to rotational symmetry about the cone axis, the average position α Euler angle ave_pos_alpha is dropped from the model. The symmetry also collapses the eigenframe to a single zaxis defined by the parameters axis_theta and axis_phi.
 `iso cone, torsionless' 
 The isotropic cone model with the torsion angle cone_sigma_max set to zero.
 `iso cone, free rotor' 
 The isotropic cone model with no torsion angle restriction.
 `rotor' 
 The only motion is a rotation about the cone axis restricted by the torsion angle cone_sigma_max.
 `rigid' 
 No domain motions.
 `free rotor' 
 The only motion is free rotation about the cone axis.
 `double rotor' 
 Restricted motions about two independent but orthogonal rotor axes. The first rotation is about the yaxis and the second is about the xaxis.
To select the isotropic cone model, type:
[numbers=none]
relax> frame_order.select_model(model='iso cone')
The relax user manual (PDF), created 20200826.