__init__(self, derivs, num_atoms=None, num_modes=None, reader=None): 

__len__(self): 

@property
n(self): 

@property
num_modes(self): 

@property
third_derivs(self): 

@property
fourth_derivs(self): 

@property
third_deriv_array(self): 

@property
fourth_deriv_array(self):