Update USAGE.md

docs/USAGE.md

@@ -39,15 +39,17 @@
 
 - Set LAMBDA_D_K (the Debye length in Angstroms) parameter in the INCAR file to use the linearized Poisson-Boltzmann model(electrolyte model)
 ```
-The VASP choice of the electrostatic reference potential sets the average potential
-in the simulation cell to zero, not the potential in the electrolyte region. To correct
-the reference electrostatic reference potential, the constant, FERMI_SHIFT, which is
-printed out to stdout, needs to be added to the Fermi level. The sign of the shift
-becomes apparent once you plot the x-y averaged local potential in the z-direction.
-Without the shift, the electrostatic potential would not go to zero in the bulk of the
-electrolyte as expected from the Poisson-Boltzmann solution.
-Furthermore, if you shift the electrostatic potential to align the potential in the
-electrolyte region to zero, or any other value, you also need to add a correction to
-the energy of your system. This correction is given by Q V, where  Q is the net charge
-of the simulation cell and V the shift in reference potential, e.g., V = FERMI_SHIFT. 
+    The VASP choice of the electrostatic reference potential sets the average potential
+    in the simulation cell to zero, not the potential in the electrolyte region. To
+    correct the reference electrostatic reference potential, the constant, FERMI_SHIFT,
+    which is printed out to stdout, needs to be added to the Fermi level. The sign of
+    the shift becomes apparent once you plot the x-y averaged local potential in
+    the z-direction. Without the shift, the electrostatic potential would not go to zero
+    in the bulk of the electrolyte as expected from the Poisson-Boltzmann solution.
+    
+    Furthermore, if you shift the electrostatic potential to align the potential in the
+    electrolyte region to zero, or any other value, you also need to add a correction to
+    the energy of your system. This correction is given by Q V, where  Q is the net
+    charge of the simulation cell and V the shift in reference potential, e.g.,
+    V = FERMI_SHIFT. 
 ```