def calculate_fy_op_finite_difference(_gto, nucleus):
"""
Calculate the operator derivative in the y-direction using
a finite difference method
"""
# build integrator object
integrator = PyQInt()
diff = 0.000001
nucleus[1] -= diff / 2.0
left = integrator.nuclear_gto(_gto, _gto, nucleus)
nucleus[1] += diff
right = integrator.nuclear_gto(_gto, _gto, nucleus)
return (right - left) / diff
def calculate_fy_bf_finite_difference(_gto, nucleus):
"""
Calculate the basis function derivative in the y-direction using
a finite difference method
"""
# build integrator object
integrator = PyQInt()
diff = 0.01
gto1 = gto(0.154329, [_gto.p[0], _gto.p[1] - diff / 2, _gto.p[2]],
3.425251, _gto.l, _gto.m, _gto.n)
gto2 = gto(0.154329, [_gto.p[0], _gto.p[1] + diff / 2, _gto.p[2]],
3.425251, _gto.l, _gto.m, _gto.n)
left = integrator.nuclear_gto(gto1, gto1, nucleus)
right = integrator.nuclear_gto(gto2, gto2, nucleus)
return (right - left) / diff
def test_gto_nuclear(self):
"""
Test nuclear attraction integral for GTOs
V^{(c)}_ij = <gto_i | -1 / |r-Rc| | gto_j>
"""
# construct integrator object
integrator = PyQInt()
# test GTO
gto1 = gto(0.154329, [0.0, 0.0, 0.0], 3.425251, 0, 0, 0)
gto2 = gto(0.535328, [0.0, 0.0, 0.0], 0.623914, 0, 0, 0)
gto3 = gto(0.444635, [0.0, 0.0, 0.0], 0.168855, 0, 0, 0)
nuclear = integrator.nuclear_gto(gto1, gto1, [0.0, 0.0, 1.0])
result = -0.31049036979675293
np.testing.assert_almost_equal(nuclear, result, 4)