Merge pull request #232 from ICAMS/faster_liquid

Faster liquid

Author: srmnitc

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.6.4
+current_version = 1.6.5
 commit = True
 tag = True
 

calphy/__init__.py

@@ -4,7 +4,7 @@
 from calphy.alchemy import Alchemy
 from calphy.routines import MeltingTemp
 
-__version__ = "1.6.4"
+__version__ = "1.6.5"
 
 def addtest(a,b):
     return a+b

calphy/input.py

@@ -49,7 +49,7 @@
 from ase.io import read, write
 import shutil
 
-__version__ = "1.6.4"
+__version__ = "1.6.5"
 
 
 def _check_equal(val):
@@ -317,7 +317,7 @@ class Calculation(BaseModel, title="Main input class"):
     _temperature_stop: float = PrivateAttr(default=None)
     _temperature_input: float = PrivateAttr(default=None)
 
-    melting_cycle: Annotated[bool, Field(default=True)]
+    melting_cycle: Annotated[bool, Field(default=False)]
 
     pair_style: Annotated[
         Union[List[str], None], BeforeValidator(to_list), Field(default=None)

calphy/liquid.py

@@ -58,6 +58,36 @@ def __init__(self, calculation=None, simfolder=None, log_to_screen=False):
             calculation=calculation, simfolder=simfolder, log_to_screen=log_to_screen
         )
 
+    def rattle_structure(self, lmp):
+        """
+        Disorder the structure using random displacements followed by a
+        controlled NVT cool-down before liquid equilibration.
+
+        This is a lightweight alternative to :meth:`melt_structure`:
+        """
+        self.logger.info(
+            "Rattling structure: velocities at 2*thigh=%f, NVT cool-down to T=%f",
+            self.calc._temperature_high,
+            self.calc._temperature,
+        )
+        lmp.command(
+            "displace_atoms all random 0.1 0.1 0.1 %d" % np.random.randint(1, 10000)
+        )
+        lmp.velocity(
+            "all create",
+            2.0 * self.calc._temperature_high,
+            np.random.randint(1, 10000),
+        )
+        lmp.command(
+            "fix              nh_rattle all nvt temp %f %f %f"
+            % (
+                self.calc._temperature_high,
+                self.calc._temperature,
+            )
+        )
+        lmp.run(int(self.calc.md.n_small_steps))
+        lmp.command("unfix            nh_rattle")
+
     def melt_structure(self, lmp):
         """ """
         if self.calc._fix_lattice and self.calc.melting_cycle:
@@ -163,9 +193,11 @@ def run_averaging(self):
         lmp.command("variable         mlz equal lz")
         lmp.command("variable         mpress equal press")
 
-        # MELT
+        # Disorder the structure before equilibration
         if self.calc.melting_cycle:
             self.melt_structure(lmp)
+        else:
+            self.rattle_structure(lmp)
 
         if not self.calc._fix_lattice:
             # now assign correct temperature and equilibrate

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "calphy"
-version = "1.6.4"
+version = "1.6.5"
 description = "free energy calculation for python"
 readme = "README.md"
 license = "GPL-3.0-only"