Update README.md

Author: apoorv-kushwaha

README.md

@@ -6,9 +6,14 @@
 # PES2MP
 The program (with GUI Interface) can generate Psi4-based potential energy surface internally (with capabilities to create input files for Gaussian, Molpro, and Psi4 for external calculations) for atom-atom (1D), rigid rotor(RR)-atom (2D), and RR-RR (4D) collision. A TensorFlow (keras) based neural-networks model can be created to augment the surface with a high degree of accuracy (at both minima and high energy regions), OR (if angular augmentation is not necessary) radial terms for each angle(s) can be analytically fitted to get missing R values. Finally, the PES is fitted into Legendre (2D) and Bispherical Harmonics (4D) to get radial terms which can be used to study rotational transitions induced by the collider. The codes are useful while studying collisional :boom: dynamics of one or both species at cold :snowflake: and ultracold :snowman: temperatures. 
 
-<details><summary>⚙️ Installation Instructions:</summary>
+<details><summary><h3>⚙️ Installation Instructions:<h3></summary>
+
+<p align="center">
+  <img src="img/installer_gui.png" alt="screenshot" width="650"/>
+</p>
+
+<!--COMMENTED ![screenshot](/img/installer_gui.png) -->
 
-![screenshot](/img/installer_gui.png)
 
 ### GUI Installation
 - run ``python3 installer_pes2mp.py``
@@ -32,7 +37,7 @@ The makefiles (inside the `make_scripts folder`) are tested on Linux and MacOS.
 - run ``./install_pes2mp_quick.sh``<br />
   </details>
 
-<details><summary>🚀 Running PES2MP: </summary>
+<details><summary><h3>🚀 Running PES2MP: <h3></summary>
 
 ### Running PES2MP
 The program can be run by keeping the input file (e.g. pesgen1D.py) and Python program files together. 
@@ -84,7 +89,12 @@ To be updated:
 - (a) Full programmer's guide 
 - :mailbox_with_mail: dhilip@iitrpr.ac.in
 
-![screenshot](/img/pes2mp_gui.png)
+
+<p align="center">
+  <img src="img/pes2mp_gui.png" alt="screenshot" width="750"/>
+</p>
+
+<!--COMMENTED ![screenshot](/img/pes2mp_gui.png) -->
 
 
 ## PES Generation :: 1D/2D/4D rigid rotor PES.