diff --git a/seamm_ase/seamm_ase.py b/seamm_ase/seamm_ase.py
index 27adf7d..ed69206 100644
--- a/seamm_ase/seamm_ase.py
+++ b/seamm_ase/seamm_ase.py
@@ -2,11 +2,16 @@
 
 __all__ = ["SEAMM_Calculator"]
 
+import logging
+
 from ase.calculators.calculator import (
     Calculator as ASE_Calculator,
     all_changes as ASE_all_changes,
+    register_calculator_class,
 )
 
+logger = logging.getLogger(__name__)
+
 
 class SEAMM_Calculator(ASE_Calculator):
     """Generic ASE calculator for SEAMM.
@@ -60,7 +65,7 @@ def calculator(
     implemented_properties = ["energy", "forces"]
     nolabel = True
 
-    def __init__(self, step, **kwargs):
+    def __init__(self, step, calculator=None, name=None, configuration=None, **kwargs):
         """
         Parameters
         ----------
@@ -71,8 +76,26 @@ def __init__(self, step, **kwargs):
             The keyword arguments are passed to the parent class.
         """
         self.step = step
+        self.calculator = calculator  # Method or function to call
+        self._name = name
+        self._configuration = configuration
+
         super().__init__(**kwargs)
 
+    @property
+    def configuration(self):
+        """The configuration this calculator represents."""
+        return self._configuration
+
+    @property
+    def name(self):
+        """A name for this calculator."""
+        if self._name is None and self.configuration is not None:
+            name = self.configuration.system.name + "/" + self.configuration.name
+            return name
+        else:
+            return self._name
+
     def calculate(
         self,
         atoms=None,
@@ -97,4 +120,25 @@ def calculate(
         """
         super().calculate(atoms, properties, system_changes)
 
-        self.step.calculator(self, properties, system_changes)
+        logger.debug(f"SEAMM_Calculator.calculate {self.name} {properties=}")
+        logger.debug(f"    {system_changes=}")
+        logger.debug(f"    {atoms is None=}")
+
+        if self.calculator is None:
+            self.step.calculate(self, properties, system_changes)
+        else:
+            self.calculator(self, properties, system_changes)
+
+    def check_state(self, atoms, tol=1e-10):
+        """Check for any system changes since last calculation."""
+        return super().check_state(atoms, tol=tol)
+
+    def get_property(self, name, atoms=None, allow_calculation=True):
+        logger.debug(f"SEAMM_Calculator.get_property {self.name} {name=}")
+
+        return super().get_property(
+            name, atoms=atoms, allow_calculation=allow_calculation
+        )
+
+
+register_calculator_class("seamm", SEAMM_Calculator)