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examples/ao2mo/04-dirac_hf_mo_integrals.py

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+#!/usr/bin/env python
+
+'''
+MO integral transformation for spinor integrals
+'''
+
+import h5py
+from pyscf import gto
+from pyscf import scf
+from pyscf import lib
+from pyscf.ao2mo import r_outcore
+
+mol = gto.M(
+    atom = '''
+    O   0.   0.       0.
+    H   0.   -0.757   0.587
+    H   0.   0.757    0.587
+    ''',
+    basis = 'sto3g',
+)
+
+mf = scf.DHF(mol).run()
+
+n4c, nmo = mf.mo_coeff.shape
+n2c = n4c // 2
+nNeg = nmo // 2
+mo = mf.mo_coeff[:n2c,nNeg:]
+r_outcore.general(mol, (mo, mo, mo, mo), 'llll.h5', intor='int2e_spinor')
+with h5py.File('llll.h5', 'r') as f:
+    print('Number of DHF molecular orbitals %s' % (nmo//2))
+    print('MO integrals for large component orbitals. Shape = %s'
+          % str(f['eri_mo'].shape))

examples/ao2mo/22-rkb_no_pair_ints.py

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+#!/usr/bin/env python
+
+'''
+Integral transformation to compute 2-electron integrals for no-pair
+Dirac-Coulomb Hamiltonian. The molecular orbitals are based on RKB basis.
+'''
+
+import h5py
+from pyscf import gto
+from pyscf import scf
+from pyscf import lib
+from pyscf.ao2mo import r_outcore
+
+mol = gto.M(
+    atom = '''
+    O   0.   0.       0.
+    H   0.   -0.757   0.587
+    H   0.   0.757    0.587
+    ''',
+    basis = 'ccpvdz',
+)
+
+mf = scf.DHF(mol).run()
+
+def no_pair_ovov(mol, mo_coeff, erifile):
+    '''
+    2-electron integrals ( o v | o v ) for no-pair Hamiltonian under RKB basis
+    '''
+    c = lib.param.LIGHT_SPEED
+    n4c, nmo = mo_coeff.shape
+    n2c = n4c // 2
+    nNeg = nmo // 2
+    nocc = mol.nelectron
+    nvir = nmo // 2 - nocc
+    mo_pos_l = mo_coeff[:n2c,nNeg:]
+    mo_pos_s = mo_coeff[n2c:,nNeg:] * (.5/c)
+    Lo = mo_pos_l[:,:nocc]
+    So = mo_pos_s[:,:nocc]
+    Lv = mo_pos_l[:,nocc:]
+    Sv = mo_pos_s[:,nocc:]
+
+    dataname = 'dhf_ovov'
+    def run(mos, intor):
+        r_outcore.general(mol, mos, erifile,
+                          dataname='tmp', intor=intor)
+        blksize = 400
+        nij = mos[0].shape[1] * mos[1].shape[1]
+        with h5py.File(erifile) as feri:
+            for i0, i1 in lib.prange(0, nij, blksize):
+                buf = feri[dataname][i0:i1]
+                buf += feri['tmp'][i0:i1]
+                feri[dataname][i0:i1] = buf
+
+    r_outcore.general(mol, (Lo, Lv, Lo, Lv), erifile,
+                      dataname=dataname, intor='int2e_spinor')
+    run((So, Sv, So, Sv), 'int2e_spsp1spsp2_spinor')
+    run((So, Sv, Lo, Lv), 'int2e_spsp1_spinor'     )
+    run((Lo, Lv, So, Sv), 'int2e_spsp2_spinor'     )
+
+no_pair_ovov(mol, mf.mo_coeff, 'dhf_ovov.h5')
+with h5py.File('dhf_ovov.h5', 'r') as f:
+    nocc = mol.nelectron
+    nvir = mol.nao * 2 - nocc
+    print('Number of DHF occupied orbitals %s' % nocc)
+    print('Number of DHF virtual orbitals in positive states %s' % nvir)
+    print('No-pair MO integrals (ov|ov) have shape %s' % str(f['dhf_ovov'].shape))
+
+