restarting

pyblock2/driver/core.py

@@ -2836,6 +2836,8 @@ def dmrg(
         store_wfn_spectra=True,
         spectra_with_multiplicity=False,
         lowmem_noise=False,
+        sweep_start=0,
+        forward=None,
     ):
         bw = self.bw
         if bond_dims is None:
@@ -2893,15 +2895,18 @@ def dmrg(
         if n_sweeps == -1:
             return None
         me.init_environments(iprint >= 2)
+        if forward is None:
+            forward = ket.center == 0
         if twosite_to_onesite is None:
-            ener = dmrg.solve(n_sweeps, ket.center == 0, tol)
+            ener = dmrg.solve(n_sweeps, forward, tol, sweep_start)
         else:
             assert twosite_to_onesite < n_sweeps
-            ener = dmrg.solve(twosite_to_onesite, ket.center == 0, 0)
-            dmrg.me.dot = 1
-            for ext_me in dmrg.ext_mes:
-                ext_me.dot = 1
-            ener = dmrg.solve(n_sweeps, ket.center == 0, tol, twosite_to_onesite)
+            if sweep_start < twosite_to_onesite:
+                ener = dmrg.solve(twosite_to_onesite, forward, 0, sweep_start)
+                dmrg.me.dot = 1
+                for ext_me in dmrg.ext_mes:
+                    ext_me.dot = 1
+            ener = dmrg.solve(n_sweeps, forward, tol, twosite_to_onesite)
             ket.dot = 1
             if self.mpi is not None:
                 self.mpi.barrier()
@@ -3788,6 +3793,7 @@ def align_mps_center(self, ket, ref):
         if self.mpi is not None:
             self.mpi.barrier()
 
+    # if restarting from the middle, this method should not be used
     def adjust_mps(self, ket, dot=None):
         if dot is None:
             dot = ket.dot

src/dmrg/sweep_algorithm.hpp

@@ -113,6 +113,7 @@ template <typename S, typename FL, typename FLS> struct DMRG {
     int davidson_def_max_size = 50;
     double tprt = 0, teig = 0, teff = 0, tmve = 0, tblk = 0, tdm = 0, tsplt = 0,
            tsvd = 0, torth = 0;
+    double accumulated_elapsed_time = 0;
     bool print_connection_time = false;
     // store all wfn singular values (for analysis) at each site
     bool store_wfn_spectra = false;
@@ -2332,7 +2333,7 @@ template <typename S, typename FL, typename FLS> struct DMRG {
         Timer start, current;
         start.get_time();
         current.get_time();
-        energies.resize(sweep_start);
+        energies.resize(sweep_start, vector<FPLS>(1, (FPLS)(FPS)0.0));
         discarded_weights.resize(sweep_start);
         mps_quanta.resize(sweep_start);
         bool converged;
@@ -2370,7 +2371,9 @@ template <typename S, typename FL, typename FLS> struct DMRG {
             double tswp = current.get_time();
             if (iprint >= 1) {
                 cout << "Time elapsed = " << fixed << setw(10)
-                     << setprecision(3) << current.current - start.current;
+                     << setprecision(3)
+                     << current.current - start.current +
+                            accumulated_elapsed_time;
                 cout << fixed << setprecision(10);
                 if (get<0>(sweep_results).size() == 1)
                     cout << " | E = " << setw(18) << get<0>(sweep_results)[0];
@@ -2488,6 +2491,7 @@ template <typename S, typename FL, typename FLS> struct DMRG {
                 break;
         }
         this->forward = forward;
+        accumulated_elapsed_time += current.current - start.current;
         if (!converged && iprint > 0 && tol != 0)
             cout << "ATTENTION: DMRG is not converged to desired tolerance of "
                  << scientific << tol << endl;