Update README.md

README.md

@@ -24,3 +24,29 @@ pip install pyscf
 PySCF is used for the computation of one- and two-electron integrals. 
 
 # Quick start
+
+```
+QuAcK 💩 % python3 PyDuck.py -h
+usage: PyDuck.py [-h] -b BASIS [--bohr] [-c CHARGE] [--cartesian] [-fc FROZEN_CORE] [-m MULTIPLICITY] [--working_dir WORKING_DIR] -x XYZ
+
+This script is the main script of QuAcK, it is used to run the calculation. If $QUACK_ROOT is not set, $QUACK_ROOT is replaces by the current
+directory.
+
+options:
+  -h, --help            show this help message and exit
+  -b BASIS, --basis BASIS
+                        Name of the file containing the basis set in the $QUACK_ROOT/basis/ directory
+  --bohr                By default QuAcK assumes that the xyz files are in Angstrom. Add this argument if your xyz file is in Bohr.
+  -c CHARGE, --charge CHARGE
+                        Total charge of the molecule. Specify negative charges with "m" instead of the minus sign, for example m1 instead of -1.
+                        Default is 0
+  --cartesian           Add this option if you want to use cartesian basis functions.
+  -fc FROZEN_CORE, --frozen_core FROZEN_CORE
+                        Freeze core MOs. Default is false
+  -m MULTIPLICITY, --multiplicity MULTIPLICITY
+                        Number of unpaired electrons 2S. Default is 0 therefore singlet
+  --working_dir WORKING_DIR
+                        Set a working directory to run the calculation.
+  -x XYZ, --xyz XYZ     Name of the file containing the nuclear coordinates in xyz format in the $QUACK_ROOT/mol/ directory without the .xyz
+                        extension
+'''