More doc improvement.

README.md

@@ -1,11 +1,13 @@
 # Introduction
 
-MatCalc is a python library for calculating materials properties using machine learning interatomic potentials.
+MatCalc is a python library for calculating materials properties using machine learning interatomic potentials (MLIPs).
+Calculating various materials properties can require relatively involved setup of various simulation codes. The
+goal of MatCalc is to provide a simplified interface to access these properties with any MLIP.
 
 # Outline
 
 The main base class in MatCalc is PropCalc (property calculator). All PropCalc subclasses should implement a
 `calc(structure) -> dict` method that takes in a Pymatgen Structure and returns a dict of properties.
 
-In general, PropCalc should be initialized with a model, which is then used by either ASE or LAMMPS or some
-other simulation code to perform calculations of properties.
+In general, PropCalc should be initialized with an ML model or ASE calculator, which is then used by either ASE,
+LAMMPS or some other simulation code to perform calculations of properties.