add more methods to DeepPot (#175)

* add get_ntypes and get_type_map methods to DeepPot

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

* add get_dim_fparam and get_dim_aparam

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

---------

Signed-off-by: Jinzhe Zeng <jinzhe.zeng@rutgers.edu>

deepmd_pt/infer/deep_eval.py

@@ -9,6 +9,7 @@
 from typing import Callable, Optional, Tuple, Union, List
 from deepmd_pt.utils import env
 from deepmd_pt.utils.auto_batch_size import AutoBatchSize
+from deepmd_utils.infer.deep_pot import DeepPot as DeepPotBase
 
 
 class DeepEval:
@@ -53,7 +54,7 @@ def eval(
         raise NotImplementedError
 
 
-class DeepPot(DeepEval):
+class DeepPot(DeepEval, DeepPotBase):
     def __init__(
         self,
         model_file: "Path",
@@ -177,6 +178,22 @@ def _eval_model(
         else:
             return energy_out, force_out, virial_out, atomic_energy_out, atomic_virial_out
 
+    def get_ntypes(self) -> int:
+        """Get the number of atom types of this model."""
+        return len(self.type_map)
+
+    def get_type_map(self) -> List[str]:
+        """Get the type map (element name of the atom types) of this model."""
+        return self.type_map
+
+    def get_dim_fparam(self) -> int:
+        """Get the number (dimension) of frame parameters of this DP."""
+        return 0
+
+    def get_dim_aparam(self) -> int:
+        """Get the number (dimension) of atomic parameters of this DP."""
+        return 0
+
 
 # For tests only
 def eval_model(