def _gamma1_intermediates(mp, mo_coeff, mo_energy, nocc, t2=None):
nmo = mo_coeff.shape[1]
nvir = nmo - nocc
from pyscf.mp import mp2
eia = mo_energy[:nocc, None] - mo_energy[None, nocc:]
if (t2 is None):
for istep, qov in enumerate(mp.loop_ao2mo(mo_coeff, nocc)):
if (istep == 0):
dtype = qov.dtype
dm1occ = np.zeros((nocc, nocc), dtype=dtype)
dm1vir = np.zeros((nvir, nvir), dtype=dtype)
for i in range(nocc):
buf = np.dot(qov[:, i * nvir:(i + 1) * nvir].T,
qov).reshape(nvir, nocc, nvir)
gi = np.array(buf, copy=False)
gi = gi.reshape(nvir, nocc, nvir).transpose(1, 0, 2)
t2i = gi / lib.direct_sum('jb+a->jba', eia, eia[i])
l2i = t2i.conj()
dm1vir += np.einsum('jca,jcb->ba', l2i, t2i) * 2 \
- np.einsum('jca,jbc->ba', l2i, t2i)
dm1occ += np.einsum('iab,jab->ij', l2i, t2i) * 2 \
- np.einsum('iab,jba->ij', l2i, t2i)
else:
dtype = t2[0].dtype
dm1occ = np.zeros((nocc, nocc), dtype=dtype)
dm1vir = np.zeros((nvir, nvir), dtype=dtype)
for i in range(nocc):
t2i = t2[i]
l2i = t2i.conj()
dm1vir += np.einsum('jca,jcb->ba', l2i, t2i) * 2 \
- np.einsum('jca,jbc->ba', l2i, t2i)
dm1occ += np.einsum('iab,jab->ij', l2i, t2i) * 2 \
- np.einsum('iab,jba->ij', l2i, t2i)
return -dm1occ, dm1vir
def get_t2(mp, mo_coeff, mo_energy, nocc):
'''basically identical to the DFMP2 kernel, returns t2'''
from pyscf.mp import mp2
nmo = mo_coeff.shape[1]
nvir = nmo - nocc
eia = mo_energy[:nocc, None] - mo_energy[None, nocc:]
emp2 = 0
t2 = []
for istep, qov in enumerate(mp.loop_ao2mo(mo_coeff, nocc)):
for i in range(nocc):
buf = np.dot(qov[:, i * nvir:(i + 1) * nvir].T,
qov).reshape(nvir, nocc, nvir)
gi = np.array(buf, copy=False)
gi = gi.reshape(nvir, nocc, nvir).transpose(1, 0, 2)
t2i = gi.conj() / lib.direct_sum('jb+a->jba', eia, eia[i])
t2.append(t2i)
emp2 += np.einsum('jab,jab', t2i, gi) * 2
emp2 -= np.einsum('jab,jba', t2i, gi)
return emp2, t2