Memory usage estimation for fc3 calculation using symfc

phono3py/cui/create_force_constants.py

@@ -274,7 +274,8 @@ def parse_forces(
             distance_to_A=physical_units["distance_to_A"],
             force_to_eVperA=physical_units["force_to_eVperA"],
         )
-    assert dataset is not None
+    if dataset is None:
+        raise RuntimeError("Dataset is not found.")
 
     if "natom" in dataset and dataset["natom"] != natom:
         raise RuntimeError(

phono3py/cui/phono3py_argparse.py

@@ -770,6 +770,14 @@ def get_parser(fc_symmetry=False, is_nac=False, load_phono3py_yaml=False):
         default=None,
         help="Use symfc for generating force constants",
     )
+    if load_phono3py_yaml:
+        parser.add_argument(
+            "--symfc-memshow",
+            dest="show_symfc_memory_usage",
+            action="store_true",
+            default=None,
+            help="Show symfc memory usage with respect to cutoff distance",
+        )
     parser.add_argument(
         "--spf",
         dest="is_spectral_function",

phono3py/cui/phono3py_script.py

@@ -95,6 +95,7 @@
     write_fc3_to_hdf5,
     write_phonon_to_hdf5,
 )
+from phono3py.interface.fc_calculator import estimate_symfc_memory_usage
 from phono3py.interface.phono3py_yaml import Phono3pyYaml
 from phono3py.phonon.grid import get_grid_point_from_address, get_ir_grid_points
 from phono3py.phonon3.dataset import forces_in_dataset
@@ -1042,6 +1043,30 @@ def main(**argparse_control):
             "and supercell structures."
         )
 
+    ###############################
+    # Memory estimation for symfc #
+    ###############################
+    if settings.show_symfc_memory_usage and load_phono3py_yaml:
+        print("Quick estimation of memory size required for solving fc3 by symfc")
+        vecs, _ = ph3py.primitive.get_smallest_vectors()
+        dists = np.unique(
+            np.round(np.linalg.norm(vecs @ ph3py.primitive.cell, axis=-1), decimals=1)
+        )
+        print("cutoff   memsize")
+        print("------   -------")
+        for cutoff in dists[1:] + 0.1:
+            memsize, memsize2 = estimate_symfc_memory_usage(
+                ph3py.supercell, ph3py.symmetry, cutoff
+            )
+            print(
+                f"{cutoff:5.1f}  {memsize + memsize2:6.2f} GB "
+                f"({memsize:.2f}+{memsize2:.2f})"
+            )
+
+        if log_level:
+            print_end_phono3py()
+        sys.exit(0)
+
     ##################
     # Check settings #
     ##################

phono3py/cui/settings.py

@@ -95,6 +95,7 @@ class Phono3pySettings(Settings):
         "sigma_cutoff_width": None,
         "solve_collective_phonon": False,
         "emulate_v2": False,
+        "show_symfc_memory_usage": False,
         "subtract_forces": None,
         "subtract_forces_fc2": None,
         "temperatures": None,
@@ -323,6 +324,10 @@ def set_solve_collective_phonon(self, val):
         """Set solve_collective_phonon."""
         self._v["solve_collective_phonon"] = val
 
+    def set_show_symfc_memory_usage(self, val):
+        """Set show_symfc_memory_usage."""
+        self._v["show_symfc_memory_usage"] = val
+
     def set_subtract_forces(self, val):
         """Set subtract_forces."""
         self._v["subtract_forces"] = val
@@ -615,6 +620,10 @@ def _read_options(self):
             if self._args.solve_collective_phonon:
                 self._confs["collective_phonon"] = ".true."
 
+        if "show_symfc_memory_usage" in self._args:
+            if self._args.show_symfc_memory_usage:
+                self._confs["show_symfc_memory_usage"] = ".true."
+
         if "subtract_forces" in self._args:
             if self._args.subtract_forces:
                 self._confs["subtract_forces"] = self._args.subtract_forces
@@ -695,6 +704,7 @@ def _parse_conf(self):
                 "N_U",
                 "spectral_function",
                 "reducible_collision_matrix",
+                "show_symfc_memory_usage",
                 "symmetrize_fc2",
                 "symmetrize_fc3_q",
                 "symmetrize_fc3_r",
@@ -1035,6 +1045,12 @@ def _set_settings(self):
         if "scattering_event_class" in params:
             self._settings.set_scattering_event_class(params["scattering_event_class"])
 
+        # Show symfc memory usage
+        if "show_symfc_memory_usage" in params:
+            self._settings.set_show_symfc_memory_usage(
+                params["show_symfc_memory_usage"]
+            )
+
         # Cutoff width of smearing function (ratio to sigma value)
         if "sigma_cutoff_width" in params:
             self._settings.set_sigma_cutoff_width(params["sigma_cutoff_width"])

phono3py/interface/fc_calculator.py

@@ -39,6 +39,7 @@
 from typing import Optional, Union
 
 import numpy as np
+from phonopy.interface.symfc import SymfcFCSolver
 from phonopy.structure.atoms import PhonopyAtoms
 from phonopy.structure.cells import Primitive
 from phonopy.structure.symmetry import Symmetry
@@ -173,3 +174,21 @@ def update_cutoff_fc_calculator_options(
             fc_calc_opts = f"cutoff = {cutoff_pair_distance}"
 
     return fc_calc_opts
+
+
+def estimate_symfc_memory_usage(
+    supercell: PhonopyAtoms, symmetry: Symmetry, cutoff: float, batch_size: int = 100
+):
+    """Estimate memory usage to run symfc for fc3 with cutoff.
+
+    Total memory usage is memsize + memsize2. These are separated because
+    they behave differently with respect to cutoff distance.
+
+    batch_size is hardcoded to 100 because it is so in symfc.
+
+    """
+    symfc_solver = SymfcFCSolver(supercell, symmetry, options={"cutoff": {3: cutoff}})
+    basis_size = symfc_solver._symfc.estimate_basis_size(orders=[3])[3]
+    memsize = basis_size**2 * 3 * 8 / 10**9
+    memsize2 = len(supercell) * 3 * batch_size * basis_size * 8 / 10**9
+    return memsize, memsize2