Issues #54 and #65: fcisolver max_memory?

PySCF apparently wants "remaining memory" on entry to fcisolver
kernel. CSFSolver currently wants "maximum memory" (the config
input by user) instead. Fix calling lines in LASSCF functions to
the CSFSolver behavior for now. Maybe the CSFSolver behavior needs
to change? Maybe the PySCF behavior needs to change?

my_pyscf/fci/csf.py

@@ -92,6 +92,10 @@ def make_hdiag_csf (h1e, eri, norb, nelec, transformer, hdiag_det=None, max_memo
         csd_offset = npair_csd_offset[ipair]
         det_addr = transformer.csd_mask[csd_offset:][:nconf*ndet]
         # mem safety
+        # Issue #54: PySCF wants "max_memory" on entrance to FCI to be "remaining memory". However,
+        # the first few lines of this function consume some memory, so that's difficult to
+        # implement consistently. "max_memory" here is currently the config parameter for the whole
+        # calculation.
         mem_remaining = max_memory - lib.current_memory ()[0]
         safety_factor = 1.2
         nfloats = nconf*ndet*ndet + det_addr.size 
@@ -284,6 +288,9 @@ def pspace (fci, h1e, eri, norb, nelec, transformer, hdiag_det=None, hdiag_csf=N
     safety_factor = 1.2
     nfloats_h0 = (npsp_det+npsp)**2
     mem_h0 = safety_factor * nfloats_h0 * np.dtype (float).itemsize / 1e6
+    # Issue #54: PySCF wants "max_memory" on entrance to FCI to be "remaining memory". However,
+    # the earlier lines of this function consume some memory, so that's difficult to implement
+    # consistently. "max_memory" here is currently the config parameter for the whole calculation.
     mem_remaining = max_memory - lib.current_memory ()[0]
     memstr = ("pspace_size of {} CSFs -> {} determinants requires {} MB, cf {} MB "
               "remaining memory").format (npsp, npsp_det, mem_h0, mem_remaining)

my_pyscf/mcscf/lasci.py

@@ -181,7 +181,6 @@ def get_grad_ci (las, mo_coeff=None, ci=None, h1eff_sub=None, h2eff_sub=None, ve
     for isub, (fcibox, h1e, ci0, ncas, nelecas) in enumerate (zip (
             las.fciboxes, h1eff_sub, ci, las.ncas_sub, las.nelecas_sub)):
         eri_cas = las.get_h2eff_slice (h2eff_sub, isub, compact=8)
-        max_memory = max(400, las.max_memory-lib.current_memory()[0])
         linkstrl = fcibox.states_gen_linkstr (ncas, nelecas, True)
         linkstr  = fcibox.states_gen_linkstr (ncas, nelecas, False)
         h2eff = fcibox.states_absorb_h1e(h1e, eri_cas, ncas, nelecas, .5)

my_pyscf/mcscf/lasci_sync.py

@@ -263,6 +263,8 @@ def ci_cycle (las, mo, ci0, veff, h2eff_sub, casdm1frs, log):
                                                                       las.nelecas_sub, h1eff_sub,
                                                                       ci0)):
         eri_cas = las.get_h2eff_slice (h2eff_sub, isub, compact=8)
+        #max_memory = max(400, las.max_memory-lib.current_memory()[0])
+        # Issue #54: compute max_memory here, or in fcisolver?
         orbsym = getattr (mo, 'orbsym', None)
         if orbsym is not None:
             i = ncas_cum[isub]
@@ -288,6 +290,7 @@ def ci_cycle (las, mo, ci0, veff, h2eff_sub, casdm1frs, log):
 
         e_sub, fcivec = fcibox.kernel(h1e, eri_cas, ncas, nelecas,
                                       ci0=fcivec, verbose=log,
+                                      #max_memory = max_memory issue #54
                                       ecore=e0, orbsym=orbsym)
         e_cas.append (e_sub)
         ci1.append (fcivec)

my_pyscf/mcscf/lasscf_async/crunch.py

@@ -292,10 +292,11 @@ def casci_kernel(casci, mo_coeff=None, ci0=None, verbose=logger.NOTE, envs=None)
                            (mo_coeff.shape[1], casci.ncore, ncas))
 
     # FCI
-    max_memory = max(400, casci.max_memory-lib.current_memory()[0])
+    #max_memory = max(400, casci.max_memory-lib.current_memory()[0])
+    # Issue #54: count memory here, or in FCISolver?
     e_tot, fcivec = casci.fcisolver.kernel(h1eff, eri_cas, ncas, nelecas,
                                            ci0=ci0, verbose=log,
-                                           max_memory=max_memory,
+                                           #max_memory=max_memory,
                                            ecore=energy_core)
 
     t1 = log.timer('FCI solver', *t1)

my_pyscf/mcscf/mc1step_csf.py

@@ -58,9 +58,10 @@ def contract_2e(c):
     if mc.ci_response_space > 7:
         logger.debug(mc, 'CI step by full response')
         # full response
-        max_memory = max(400, mc.max_memory-lib.current_memory()[0])
+        #max_memory = max(400, mc.max_memory-lib.current_memory()[0])
+        # Issue #54: count memory here, or in fcisolver?
         e, ci1 = mc.fcisolver.kernel(h1, h2, ncas, nelecas, ecore=ecore,
-                                       ci0=ci0, tol=tol, max_memory=max_memory)
+                                       ci0=ci0, tol=tol)#, max_memory=max_memory)
     else:
         # MRH 03/24/2019: this is where I intervene to enforce CSFs
         fci = mc.fcisolver