# HTST¶

Harmonic transition state theory.

Note that calculate_prefactor needs to be called before using any of the getter functions.

`spirit.htst.``calculate`(p_state, idx_image_minimum, idx_image_sp, n_eigenmodes_keep=-1, sparse=False, idx_chain=-1)

Performs an HTST calculation and returns rate prefactor.

Note: this function must be called before any of the getters.

`spirit.htst.``get_eigenvalues_min`(p_state, idx_chain=-1)

Returns the eigenvalues at the minimum with shape(2*nos).

`spirit.htst.``get_eigenvalues_sp`(p_state, idx_chain=-1)

Returns the eigenvalues at the saddle point with shape(2*nos).

`spirit.htst.``get_eigenvectors_min`(p_state, idx_chain=-1)

Returns a numpy array view to the eigenvectors at the minimum with shape(n_eigenmodes_keep, 2*nos).

`spirit.htst.``get_eigenvectors_sp`(p_state, idx_chain=-1)

Returns a numpy array view to the eigenvectors at the saddle point with shape(n_eigenmodes_keep, 2*nos).

`spirit.htst.``get_info`(p_state, idx_chain=-1)

Returns a set of HTST information:

• the exponent of the temperature-dependence
• me
• Omega_0
• s
• zero mode volume at the minimum
• zero mode volume at the saddle point
• dynamical prefactor
• full rate prefactor (without temperature dependent part)
`spirit.htst.``get_info_dict`(p_state, idx_chain=-1)

Returns a set of HTST information in a dictionary:

• the exponent of the temperature-dependence
• me
• Omega_0
• s
• zero mode volume at the minimum
• zero mode volume at the saddle point
• dynamical prefactor
• full rate prefactor (without temperature dependent part)
`spirit.htst.``get_velocities`(p_state, idx_chain=-1)

Returns the velocities perpendicular to the dividing surface with shape(2*nos).