diff --git a/read_structure_step/formats/mop/find_mopac.py b/read_structure_step/formats/mop/find_mopac.py
index 4b1a779..0498a67 100644
--- a/read_structure_step/formats/mop/find_mopac.py
+++ b/read_structure_step/formats/mop/find_mopac.py
@@ -6,6 +6,25 @@
 
 
 def find_mopac():
+    # Try the commandline options / config file
+    parser = seamm_util.getParser()
+    options = parser.get_options()
+
+    if "mopac-step" in options:
+        mopac_options = options["mopac-step"]
+        exe = mopac_options["mopac_exe"]
+        mopac_path = mopac_options["mopac_path"]
+        if mopac_path != "":
+            exe = str(Path(mopac_path).expanduser().resolve() / exe)
+
+        try:
+            mopac_exe = seamm_util.check_executable(exe)
+        except FileNotFoundError:
+            pass
+        else:
+            return mopac_exe
+
+    # Next try common locations
     try:
         mopac_exe = "/opt/mopac/MOPAC2016.exe"
 
@@ -14,10 +33,8 @@ def find_mopac():
                 'The directory "/opt/mopac/" exists, but the executable \
                 "MOPAC2016.exe" is not there'
             )
-
     except FileNotFoundError:
         try:
-
             mopac_path = os.path.split(os.environ["mopac"])[0]
             mopac_exe = mopac_path + "MOPAC2016.exe"
 
@@ -26,7 +43,6 @@ def find_mopac():
                     'The environment variable "mopac" is defined, but \
                             the executable "MOPAC2016.exe" is not there'
                 )
-
         except (KeyError, FileNotFoundError):
             try:
                 mopac_exe = Path(os.environ["MOPAC_LICENSE"]) / "MOPAC2016.exe"
diff --git a/read_structure_step/formats/mop/obabel.py b/read_structure_step/formats/mop/obabel.py
index 288de0b..7a98e39 100644
--- a/read_structure_step/formats/mop/obabel.py
+++ b/read_structure_step/formats/mop/obabel.py
@@ -23,16 +23,16 @@
     "CP": "constant pressure heat capacity",
     "CPR": "reference.constant pressure heat capacity",
     "D": "dipole moment",
-    "DR": "reference.dipole moment",
+    "DR": "dipole moment.reference",
     "H": "enthalpy of formation",
-    "HR": "reference.enthalpy of formation",
+    "HR": "enthalpy of formation.reference",
     "S": "entropy",
-    "SR": "reference.entropy",
+    "SR": "entropy.reference",
     "I": "ionization energy",
     "IE": "ionization energy",
     "IA": "ionization energy",
-    "IR": "reference.ionization energy",
-    "GR": "reference.geometry",
+    "IR": "ionization energy.reference",
+    "GR": "geometry.reference",
 }
 multiplicities = {
     "SINGLET": 1,
@@ -494,7 +494,7 @@ def load_mop(
     # Save keywords, description and any data encoded in the file to the database
     if save_data:
         properties = configuration.properties
-        if len("keywords") != 0:
+        if len(keywords) != 0:
             key = "MOPAC.keywords"
             properties.add(
                 key, "str", description="The keywords for MOPAC", noerror=True
@@ -536,14 +536,29 @@ def load_mop(
                                 print()
                                 continue
                             keyword = metadata[keyword]
+                            if value == "":
+                                print(f"Value for {keyword} missing in MOPAC .mop file")
+                                continue
                             if "reference" in keyword:
-                                description = keyword.split(".")[1]
+                                description = keyword.split(".")[0]
                                 properties.add(
                                     keyword,
                                     "str",
                                     description=f"Reference for the {description}.",
                                     noerror=True,
                                 )
+                            elif "," in value:
+                                # value , stderr
+                                tmp = value.split(",")
+                                value = tmp[0].strip()
+                                stderr = tmp[1].strip()
+                                properties.add(
+                                    f"{keyword}.stderr",
+                                    "float",
+                                    description=f"stderr for the {keyword}.",
+                                    noerror=True,
+                                )
+                                properties.put(f"{keyword}.stderr", stderr)
                             properties.put(keyword, value)
                         except Exception as e:
                             print(f"{e}: {key}")
diff --git a/read_structure_step/read_structure.py b/read_structure_step/read_structure.py
index a578439..10dc873 100644
--- a/read_structure_step/read_structure.py
+++ b/read_structure_step/read_structure.py
@@ -22,6 +22,7 @@
 from .read import read
 import seamm
 from seamm_util import ureg, Q_  # noqa: F401
+from seamm_util import getParser
 import seamm_util.printing as printing
 from seamm_util.printing import FormattedText as __
 from .utils import guess_extension
@@ -69,6 +70,62 @@ def git_revision(self):
         """The git version of this module."""
         return read_structure_step.__git_revision__
 
+    def create_parser(self):
+        """Setup the command-line / config file parser"""
+        # Need to mimic MOPAC step to find the MOPAC executable
+        parser_name = "mopac-step"
+        print(f"Parser {parser_name}, {self.step_type=}")
+        parser = getParser()
+
+        # Remember if the parser exists ... this type of step may have been
+        # found before
+        parser_exists = parser.exists(parser_name)
+        print(f"{parser_exists=}")
+
+        # Create the standard options, e.g. log-level
+        result = super().create_parser(name=parser_name)
+
+        if parser_exists:
+            return result
+
+        # Options for Mopac
+        parser.add_argument(
+            parser_name,
+            "--mopac-exe",
+            default="MOPAC2016.exe",
+            help="the name of the MOPAC executable",
+        )
+
+        parser.add_argument(
+            parser_name,
+            "--mopac-path",
+            default="",
+            help="the path to the MOPAC executable",
+        )
+
+        parser.add_argument(
+            parser_name,
+            "--ncores",
+            default="default",
+            help="How many threads to use in MOPAC",
+        )
+
+        parser.add_argument(
+            parser_name,
+            "--mkl-num-threads",
+            default="default",
+            help="How many threads to use with MKL in MOPAC",
+        )
+
+        parser.add_argument(
+            parser_name,
+            "--max-atoms-to-print",
+            default=25,
+            help="Maximum number of atoms to print charges, etc.",
+        )
+
+        return result
+
     def description_text(self, P=None):
         """Create the text description of what this step will do.
         The dictionary of control values is passed in as P so that