def compute_hessian(
self,
molecule: 'psi4.core.Molecule',
wfn: 'psi4.core.Wavefunction' = None) -> 'psi4.core.Matrix':
"""Compute dispersion Hessian based on engine, dispersion level, and parameters in `self`.
Uses finite difference, as no dispersion engine has analytic second derivatives.
Parameters
----------
molecule : psi4.core.Molecule
System for which to compute empirical dispersion correction.
wfn :
Location to set QCVariables
Returns
-------
psi4.core.Matrix
(3*nat, 3*nat) dispersion Hessian [Eh/a0/a0].
"""
optstash = p4util.OptionsState(['PRINT'], ['PARENT_SYMMETRY'])
core.set_global_option('PRINT', 0)
core.print_out(
"\n\n Analytical Dispersion Hessians are not supported by dftd3 or gcp.\n"
)
core.print_out(
" Computing the Hessian through finite difference of gradients.\n\n"
)
# Setup the molecule
molclone = molecule.clone()
molclone.reinterpret_coordentry(False)
molclone.fix_orientation(True)
molclone.fix_com(True)
# Record undisplaced symmetry for projection of diplaced point groups
core.set_global_option("PARENT_SYMMETRY",
molecule.schoenflies_symbol())
findif_meta_dict = driver_findif.hessian_from_gradients_geometries(
molclone, -1)
for displacement in findif_meta_dict["displacements"].values():
geom_array = np.reshape(displacement["geometry"], (-1, 3))
molclone.set_geometry(core.Matrix.from_array(geom_array))
molclone.update_geometry()
displacement["gradient"] = self.compute_gradient(
molclone).np.ravel().tolist()
H = driver_findif.assemble_hessian_from_gradients(findif_meta_dict, -1)
if wfn is not None:
wfn.set_variable('DISPERSION CORRECTION HESSIAN', H)
optstash.restore()
return core.Matrix.from_array(H)
def compute_hessian(self, molecule):
"""Compute dispersion Hessian based on engine, dispersion level, and parameters in `self`.
Uses finite difference, as no dispersion engine has analytic second derivatives.
Parameters
----------
molecule : psi4.core.Molecule
System for which to compute empirical dispersion correction.
Returns
-------
psi4.core.Matrix
(3*nat, 3*nat) dispersion Hessian [Eh/a0/a0].
"""
optstash = p4util.OptionsState(['PRINT'], ['PARENT_SYMMETRY'])
core.set_global_option('PRINT', 0)
core.print_out("\n\n Analytical Dispersion Hessians are not supported by dftd3 or gcp.\n")
core.print_out(" Computing the Hessian through finite difference of gradients.\n\n")
# Setup the molecule
molclone = molecule.clone()
molclone.reinterpret_coordentry(False)
molclone.fix_orientation(True)
molclone.fix_com(True)
# Record undisplaced symmetry for projection of diplaced point groups
core.set_global_option("PARENT_SYMMETRY", molecule.schoenflies_symbol())
findif_meta_dict = driver_findif.hessian_from_gradients_geometries(molclone, -1)
for displacement in findif_meta_dict["displacements"].values():
geom_array = np.reshape(displacement["geometry"], (-1, 3))
molclone.set_geometry(core.Matrix.from_array(geom_array))
molclone.update_geometry()
displacement["gradient"] = self.compute_gradient(molclone).np.ravel().tolist()
H = driver_findif.assemble_hessian_from_gradients(findif_meta_dict, -1)
optstash.restore()
return core.Matrix.from_array(H)