Added to_cisdtq functionality to RFCI wave function types for extract…

.github/workflows/ci.yaml

@@ -4,7 +4,6 @@ on:
   push:
     branches: [master, dev]
   pull_request:
-    branches: [master, dev]
   schedule:
     - cron: '0 2 * * *'
 

examples/ewf/molecules/04-bath-options.py

@@ -1,3 +1,4 @@
+import numpy as np
 import pyscf
 import pyscf.gto
 import pyscf.scf
@@ -45,6 +46,11 @@
 # of BNOs for a given threshold, and results in a smaller bath for a given threshold.
 # Other options (not shown) include projecting out all couplings to the DMET bath space, or just projecting
 # one index.
+# The options below are default
+emb_mp2_projdmet = vayesta.ewf.EWF(mf, bath_options=dict(bathtype='mp2', threshold=1e-4, 
+        project_dmet_order=2, project_dmet_mode='squared-entropy'))
+emb_mp2_projdmet.kernel()
+assert(np.allclose(emb_mp2_projdmet.e_tot, emb_mp2.e_tot))
 # To turn off this projection (which was not used in 10.1103/PhysRevX.12.011046),
 # use `project_dmet_order = 0`:
 bath = dict(bathtype='mp2', threshold=1e-4, project_dmet_order=0)

examples/ewf/molecules/11-fragmentation.py

@@ -21,19 +21,21 @@
 mf.kernel()
 
 # Embedded CCSD
-emb_iao = vayesta.ewf.EWF(mf, bno_threshold=1e-6)
+emb_iao = vayesta.ewf.EWF(mf, bath_options=dict(threshold=1e-6))
 # If calling the kernel without initializing the fragmentation,
-# IAO fragmentation is used automatically:
-# It can be initialized manually by calling emb.iao_fragmentation()
+# IAO fragmentation is used automatically.
+# It can be initialized manually by calling:
+with emb_iao.iao_fragmentation() as f:
+    f.add_all_atomic_fragments()
 emb_iao.kernel()
 
-emb_iaopao = vayesta.ewf.EWF(mf, bno_threshold=1e-6)
+emb_iaopao = vayesta.ewf.EWF(mf, bath_options=dict(threshold=1e-6))
 # To use IAO+PAOs, call emb.iaopao_fragmentation() before the kernel:
 with emb_iaopao.iaopao_fragmentation() as f:
     f.add_all_atomic_fragments()
 emb_iaopao.kernel()
 
-emb_sao = vayesta.ewf.EWF(mf, bno_threshold=1e-6)
+emb_sao = vayesta.ewf.EWF(mf, bath_options=dict(threshold=1e-6))
 # To use Lowdin AOs (SAOs), call emb.sao_fragmentation() before the kernel:
 with emb_sao.sao_fragmentation() as f:
     f.add_all_atomic_fragments()

examples/ewf/molecules/25-externally-correct.py

@@ -0,0 +1,62 @@
+import numpy as np
+import pyscf
+import pyscf.gto
+import pyscf.scf
+import pyscf.cc
+import pyscf.fci
+import vayesta
+import vayesta.ewf
+from vayesta.misc import molecules
+
+mol = pyscf.gto.Mole()
+mol.atom = """
+Se	0.0000	0.0000	0.2807
+O 	0.0000	1.3464	-0.5965
+O 	0.0000	-1.3464	-0.5965
+"""
+mol.basis = 'cc-pVDZ'
+mol.output = 'pyscf.out'
+mol.build()
+
+# Hartree-Fock
+mf = pyscf.scf.RHF(mol)
+mf.kernel()
+
+# Reference full system CCSD:
+cc = pyscf.cc.CCSD(mf)
+cc.kernel()
+
+# 1) Consider setup where you have a complete CCSD, externally corrected by local atomic fragment+DMET FCI clusters
+emb = vayesta.ewf.EWF(mf)
+with emb.iao_fragmentation() as f:
+    # Add all atomic FCI fragments with DMET bath
+    # Store the FCI wave functions as CCSDTQ types, so they can be used for correction later.
+    # These want to be flagged as 'auxiliary', as they are solved first, and then used as constraints for the 
+    # non-auxiliary fragments.
+    fci_frags = f.add_all_atomic_fragments(solver='FCI', bath_options=dict(bathtype='dmet'), store_wf_type='CCSDTQ', auxiliary=True)
+    # Add single 'complete' CCSD fragment covering all IAOs
+    ccsd_frag = f.add_full_system(solver='CCSD', bath_options=dict(bathtype='full'))
+# Setup the external correction from the CCSD fragment.
+# Main option is 'projectors', which should be an integer between 0 and 2 (inclusive).
+# The larger the number, the more fragment projectors are applied to the correcting T2 contributions, and less
+# 'bath' correlation from the FCI clusters is used as a constraint in the external correction of the CCSD clusters.
+# For multiple constraining fragments, proj=0 will double-count the correction due to overlapping bath spaces, and 
+# in this case, only proj=1 will be exact in the limit of enlarging (FCI) bath spaces.
+# Note that there is also the option 'low_level_coul' (default True). For the important T3 * V contribution to the
+# T2 amplitudes, this determines whether the V is expressed in the FCI or CCSD cluster space. The CCSD cluster is
+# larger, and hence this is likely to be better (and is default), as the correction is longer-ranged (though slightly more expensive).
+ccsd_frag.add_external_corrections(fci_frags, correction_type='external', projectors=1)
+emb.kernel()
+print('Total energy from full system CCSD tailored (CCSD Coulomb interaction) by atomic FCI fragments (projectors=1): {}'.format(emb.e_tot))
+
+# 2) Now, we also fragment the CCSD spaces, and use BNOs. These CCSD fragments are individually externally corrected from the FCI clusters.
+# Similar set up, but we now have multiple CCSD clusters.
+emb = vayesta.ewf.EWF(mf)
+with emb.iao_fragmentation() as f:
+    fci_frags = f.add_all_atomic_fragments(solver='FCI', bath_options=dict(bathtype='dmet'), store_wf_type='CCSDTQ', auxiliary=True)
+    ccsd_frags = f.add_all_atomic_fragments(solver='CCSD', bath_options=dict(bathtype='mp2', threshold=1.e-5))
+# Now add external corrections to all CCSD clusters, and use 'external' correction, with 2 projectors and only contracting with the FCI integrals
+for cc_frag in ccsd_frags:
+    cc_frag.add_external_corrections(fci_frags, correction_type='external', projectors=2, low_level_coul=False)
+emb.kernel()
+print('Total energy from embedded CCSD tailored (FCI Coulomb interaction) by atomic FCI fragments (projectors=2): {}'.format(emb.e_tot))

examples/ewf/other/61-ext-corr-hubbard-1D.py

@@ -0,0 +1,111 @@
+import pyscf
+import pyscf.cc
+import pyscf.fci
+import vayesta
+import vayesta.ewf
+import vayesta.lattmod
+
+nsite = 10
+nelectron = nsite
+hubbard_u = 4.0
+mol = vayesta.lattmod.Hubbard1D(nsite, nelectron=nelectron, hubbard_u=hubbard_u)
+mf = vayesta.lattmod.LatticeMF(mol)
+mf.kernel()
+assert(mf.converged)
+
+# Reference full system CCSD and FCI
+cc = pyscf.cc.CCSD(mf)
+cc.kernel()
+fci = pyscf.fci.FCI(mf)
+fci.threads = 1
+fci.conv_tol = 1e-12
+fci.davidson_only = True
+fci.kernel()
+
+# Perform embedded FCI with two sites
+emb_simp = vayesta.ewf.EWF(mf, solver='FCI', bath_options=dict(bathtype='dmet'))
+with emb_simp.site_fragmentation() as f:
+    f.add_atomic_fragment([0, 1], sym_factor=nsite/2, nelectron_target=2*nelectron/nsite)
+emb_simp.kernel()
+
+# Perform full system CCSD, externally corrected by two-site+DMET bath FCI level clusters
+emb = vayesta.ewf.EWF(mf)
+fci_frags = []
+with emb.site_fragmentation() as f:
+    # Set up a two-site FCI fragmentation of full system as auxiliary clusters
+    # Ensure the right number of electrons on each fragment space of the FCI calculation.
+    fci_frags.append(f.add_atomic_fragment([0, 1], solver='FCI', bath_options=dict(bathtype='dmet'), store_wf_type='CCSDTQ', nelectron_target=2*nelectron/nsite, auxiliary=True))
+    # Add single 'complete' CCSD fragment covering all sites
+    ccsd_frag = f.add_full_system(solver='CCSD', bath_options=dict(bathtype='full'), solver_options=dict(solve_lambda=False, init_guess='CISD'))
+# Add symmetry-derived FCI fragments to avoid multiple calculations
+fci_frags.extend(fci_frags[0].add_tsymmetric_fragments(tvecs=[5, 1, 1])
+
+e_extcorr = []
+extcorr_conv = []
+#Main options: 'projectors', which should be an integer between 0 and 2 (inclusive).
+#The larger the number, the more fragment projectors are applied to the correcting T2 contributions, and less
+#'bath' correlation from the FCI clusters is used as a constraint in the external correction of the CCSD clusters.
+#NOTE that with multiple FCI fragments providing constraints and overlapping bath spaces, proj=0 will
+#overcount the correction, so do not use with multiple FCI clusters. It will not e.g. tend to the right answer as
+#the FCI bath space becomes complete (for which you must have proj=1). Only use with a single FCI fragment.
+ccsd_frag.add_external_corrections(fci_frags, correction_type='external', projectors=1)
+emb.kernel()
+e_extcorr.append(emb.e_tot); extcorr_conv.append(emb.converged)
+
+# For subsequent calculations where we have just changed the mode/projectors in the external tailoring, we want to avoid having
+# to resolve the FCI fragments. Set them to inactive, so just the CCSD fragments will be resolved.
+for fci_frag in fci_frags:
+    fci_frag.active = False
+
+ccsd_frag.clear_external_corrections() # Clear any previous corrections applied
+ccsd_frag.add_external_corrections(fci_frags, correction_type='external', projectors=2)
+emb.kernel()
+e_extcorr.append(emb.e_tot); extcorr_conv.append(emb.converged)
+
+ccsd_frag.clear_external_corrections() # Clear any previous corrections applied
+ccsd_frag.add_external_corrections(fci_frags, correction_type='external', projectors=1, low_level_coul=False)
+emb.kernel()
+e_extcorr.append(emb.e_tot); extcorr_conv.append(emb.converged)
+
+ccsd_frag.clear_external_corrections() # Clear any previous corrections applied
+ccsd_frag.add_external_corrections(fci_frags, correction_type='external', projectors=2, low_level_coul=False)
+emb.kernel()
+e_extcorr.append(emb.e_tot); extcorr_conv.append(emb.converged)
+
+# Compare to a simpler tailoring
+e_tailor = []
+tailor_conv = []
+ccsd_frag.clear_external_corrections()
+ccsd_frag.add_external_corrections(fci_frags, correction_type='tailor', projectors=1)
+emb.kernel()
+e_tailor.append(emb.e_tot); tailor_conv.append(emb.converged)
+ccsd_frag.clear_external_corrections()
+ccsd_frag.add_external_corrections(fci_frags, correction_type='tailor', projectors=2)
+emb.kernel()
+e_tailor.append(emb.e_tot); tailor_conv.append(emb.converged)
+
+# Compare to a delta-tailoring, where the correction is the difference between full-system
+# CCSD and CCSD in the FCI cluster.
+e_dtailor = []
+dtailor_conv = []
+ccsd_frag.clear_external_corrections()
+ccsd_frag.add_external_corrections(fci_frags, correction_type='delta-tailor', projectors=1)
+emb.kernel()
+e_dtailor.append(emb.e_tot); dtailor_conv.append(emb.converged)
+ccsd_frag.clear_external_corrections()
+ccsd_frag.add_external_corrections(fci_frags, correction_type='delta-tailor', projectors=2)
+emb.kernel()
+e_dtailor.append(emb.e_tot); dtailor_conv.append(emb.converged)
+
+print("E(MF)=                                   %+16.8f Ha, conv = %s" % (mf.e_tot/nsite, mf.converged))
+print("E(CCSD)=                                 %+16.8f Ha, conv = %s" % (cc.e_tot/nsite, cc.converged))
+print("E(FCI)=                                  %+16.8f Ha, conv = %s" % (fci.e_tot/nsite, fci.converged))
+print("E(Emb. FCI, 2-site)=                     %+16.8f Ha, conv = %s" % (emb_simp.e_tot/nsite, emb_simp.converged))
+print("E(EC-CCSD, 2-site FCI, 1 proj, ccsd V)=  %+16.8f Ha, conv = %s" % ((e_extcorr[0]/nsite), extcorr_conv[0]))
+print("E(EC-CCSD, 2-site FCI, 2 proj, ccsd V)=  %+16.8f Ha, conv = %s" % ((e_extcorr[1]/nsite), extcorr_conv[1]))
+print("E(EC-CCSD, 2-site FCI, 1 proj, fci V)=   %+16.8f Ha, conv = %s" % ((e_extcorr[2]/nsite), extcorr_conv[2]))
+print("E(EC-CCSD, 2-site FCI, 2 proj, fci V)=   %+16.8f Ha, conv = %s" % ((e_extcorr[3]/nsite), extcorr_conv[3]))
+print("E(T-CCSD, 2-site FCI, 1 proj)=           %+16.8f Ha, conv = %s" % ((e_tailor[0]/nsite), tailor_conv[0]))
+print("E(T-CCSD, 2-site FCI, 2 proj)=           %+16.8f Ha, conv = %s" % ((e_tailor[1]/nsite), tailor_conv[1]))
+print("E(DT-CCSD, 2-site FCI, 1 proj)=          %+16.8f Ha, conv = %s" % ((e_dtailor[0]/nsite), dtailor_conv[0]))
+print("E(DT-CCSD, 2-site FCI, 2 proj)=          %+16.8f Ha, conv = %s" % ((e_dtailor[1]/nsite), dtailor_conv[1]))

vayesta/core/qemb/fragment.py

@@ -333,9 +333,11 @@ def cluster(self, value):
             raise RuntimeError("Cannot set attribute cluster in symmetry derived fragment.")
         self._cluster = value
 
-    def reset(self, reset_bath=True, reset_cluster=True, reset_eris=True):
-        self.log.debugv("Resetting %s (reset_bath= %r, reset_cluster= %r, reset_eris= %r)",
-                self, reset_bath, reset_cluster, reset_eris)
+    def reset(self, reset_bath=True, reset_cluster=True, reset_eris=True, reset_inactive=True):
+        self.log.debugv("Resetting %s (reset_bath= %r, reset_cluster= %r, reset_eris= %r, reset_inactive= %r)",
+                self, reset_bath, reset_cluster, reset_eris, reset_inactive)
+        if not reset_inactive and not self.active: 
+            return
         if reset_bath:
             self._dmet_bath = None
             self._bath_factory_occ = None

vayesta/core/qemb/qemb.py

@@ -1572,7 +1572,7 @@ def check_fragment_symmetry(self, dm1, symtol=1e-6):
             for child in children:
                 charge_err, spin_err = parent.get_symmetry_error(child, dm1=dm1)
                 if (max(charge_err, spin_err) > symtol):
-                    raise RuntimeError("%s and %s not symmetric! Errors:  charge= %.2e  spin= %.2e"
+                    raise SymmetryError("%s and %s not symmetric! Errors:  charge= %.2e  spin= %.2e"
                                        % (parent.name, child.name, charge_err, spin_err))
                 else:
                     self.log.debugv("Symmetry between %s and %s: Errors:  charge= %.2e  spin= %.2e",

vayesta/core/scmf/scmf.py

@@ -100,7 +100,12 @@ def kernel(self, *args, **kwargs):
 
             dm1 = self.mf.make_rdm1()
             # Check symmetry
-            self.emb.check_fragment_symmetry(dm1)
+            try:
+                self.emb.check_fragment_symmetry(dm1)
+            except SymmetryError:
+                self.log.error("Symmetry check failed in %s", self.name)
+                self.converged = False
+                break
 
             # Check convergence
             conv, de, ddm = self.check_convergence(e_tot, dm1, e_last, dm1_last)

vayesta/core/types/wf/ccsdtq.py

@@ -13,17 +13,35 @@ def CCSDTQ_WaveFunction(mo, *args, **kwargs):
 
 
 class RCCSDTQ_WaveFunction(wf_types.WaveFunction):
+    # TODO: Contract T4's down to intermediates to reduce EC-CC memory overheads.
 
     def __init__(self, mo, t1, t2, t3, t4):
         super().__init__(mo)
         self.t1 = t1
         self.t2 = t2
         self.t3 = t3
         self.t4 = t4
+        self._check_amps()
+
+    def _check_amps(self):
+        if not (isinstance(self.t4, tuple) and len(self.t4) == 2):
+            raise ValueError("t4 definition in RCCSDTQ wfn requires tuple of (abaa, abab) spin signatures")
 
     def as_ccsdtq(self):
         return self
 
+    def as_ccsd(self):
+        if self.projector is not None:
+            raise NotImplementedError
+        return wf_types.CCSD_WaveFunction(self.mo, self.t1, self.t2)
+
+    def as_cisd(self, c0=1.0):
+        return self.as_ccsd().as_cisd()
 
 class UCCSDTQ_WaveFunction(RCCSDTQ_WaveFunction):
-    pass
+    def _check_amps(self):
+        if not (isinstance(self.t3, tuple) and len(self.t3) == 4):
+            raise ValueError("t4 definition in UCCSDTQ wfn requires tuple of (aaa, aba, bab, bbb) spin signatures")
+        if not (isinstance(self.t4, tuple) and len(self.t4) == 5):
+            raise ValueError(
+                    "t4 definition in UCCSDTQ wfn requires tuple of (aaaa, aaab, abab, abbb, bbbb) spin signatures")

vayesta/core/types/wf/cisdtq.py

@@ -2,6 +2,7 @@
 import vayesta
 from vayesta.core.util import *
 from vayesta.core.types import wf as wf_types
+from vayesta.core.types.wf import t_to_c
 
 
 def CISDTQ_WaveFunction(mo, *args, **kwargs):
@@ -21,43 +22,47 @@ def __init__(self, mo, c0, c1, c2, c3, c4):
         self.c2 = c2
         self.c3 = c3
         self.c4 = c4
+        if not (isinstance(c4, tuple) and len(c4) == 2):
+            raise ValueError("c4 definition in RCISDTQ wfn requires tuple of (abaa, abab) spin signatures")
 
     def as_ccsdtq(self):
-        t1 = self.c1/self.c0
-        t2 = self.c2/self.c0 - einsum('ia,jb->ijab', t1, t1)
-        raise NotImplementedError
-        # TODO:
-        # see also THE JOURNAL OF CHEMICAL PHYSICS 147, 154105 (2017)
-        t3 = self.c3/self.c0 # - C1*C2 - (C1^3)/3
-        t4 = self.c4/self.c0 # - C1*C3 - (C2^2)/2 - C1^2*C2 - (C1^4)/4
+        c1 = self.c1 / self.c0
+        c2 = self.c2 / self.c0
+        c3 = self.c3 / self.c0
+        c4 = tuple(c / self.c0 for c in self.c4)
+
+        t1 = t_to_c.t1_rhf(c1)
+        t2 = t_to_c.t2_rhf(t1, c2)
+        t3 = t_to_c.t3_rhf(t1, t2, c3)
+        t4 = t_to_c.t4_rhf(t1, t2, t3, c4)
+
         return wf_types.RCCSDTQ_WaveFunction(self.mo, t1=t1, t2=t2, t3=t3, t4=t4)
 
 
-class UCISDTQ_WaveFunction(RCISDTQ_WaveFunction):
+class UCISDTQ_WaveFunction(wf_types.WaveFunction):
+
+    def __init__(self, mo, c0, c1, c2, c3, c4):
+        super().__init__(mo)
+        self.c0 = c0
+        self.c1 = c1
+        self.c2 = c2
+        self.c3 = c3
+        self.c4 = c4
+        if not (isinstance(c3, tuple) and len(c3) == 4):
+            raise ValueError("c4 definition in UCISDTQ wfn requires tuple of (aaa, aba, bab, bbb) spin signatures")
+        if not (isinstance(c4, tuple) and len(c4) == 5):
+            raise ValueError(
+                    "c4 definition in UCISDTQ wfn requires tuple of (aaaa, aaab, abab, abbb, bbbb) spin signatures")
 
     def as_ccsdtq(self):
-        c1a, c1b = self.c1
-        c2aa, c2ab, c2bb = self.c2
-        # TODO
-        #c3aaa, c3aab, ... = self.c3
-        #c4aaaa, c4aaab, ... = self.c4
-
-        # T1
-        t1a = c1a/self.c0
-        t1b = c1b/self.c0
-        # T2
-        t2aa = c2aa/self.c0 - einsum('ia,jb->ijab', t1a, t1a) + einsum('ib,ja->ijab', t1a, t1a)
-        t2bb = c2bb/self.c0 - einsum('ia,jb->ijab', t1b, t1b) + einsum('ib,ja->ijab', t1b, t1b)
-        t2ab = c2ab/self.c0 - einsum('ia,jb->ijab', t1a, t1b)
-        # T3
-        raise NotImplementedError
-        #t3aaa = c3aaa/self.c0 - einsum('ijab,kc->ijkabc', t2a, t1a) - ...
-        # T4
-        #t4aaaa = c4aaaa/self.c0 - einsum('ijkabc,ld->ijklabcd', t3a, t1a) - ...
-
-        t1 = (t1a, t1b)
-        t2 = (t2aa, t2ab, t2bb)
-        # TODO
-        #t3 = (t3aaa, t3aab, ...)
-        #t4 = (t4aaaa, t4aaab, ...)
+        c1 = tuple(c / self.c0 for c in self.c1)
+        c2 = tuple(c / self.c0 for c in self.c2)
+        c3 = tuple(c / self.c0 for c in self.c3)
+        c4 = tuple(c / self.c0 for c in self.c4)
+
+        t1 = t_to_c.t1_uhf(c1)
+        t2 = t_to_c.t2_uhf(t1, c2)
+        t3 = t_to_c.t3_uhf(t1, t2, c3)
+        t4 = t_to_c.t4_uhf(t1, t2, t3, c4)
+
         return wf_types.UCCSDTQ_WaveFunction(self.mo, t1=t1, t2=t2, t3=t3, t4=t4)