Quantum ESPRESSO is a suite for first-principles electronic-structure calculations and materials modeling, distributed for free and as free software under the GNU General Public License. It is based on density-functional theory, plane wave basis sets, and pseudopotentials (both norm-conserving and ultrasoft). ESPRESSO is an acronym for opEn-Source Package for Research in Electronic Structure, Simulation, and Optimization.

1. Using Quantom Espresso


2. Generating an Energy-Volume Curve


3. What is structural optimization in Quantum ESPRESSO?
   
   The idea of structural optimization is to find the structure with the minimum energy (zero force). There are two different types of structural optimization in Quantum ESPRESSO: relax and vc-relax.
   
   The vc-relax let the cell fully relax which is both the cell parameters and atom positions to its minimum energy structure (groud state structure).
   
   However, the relax mod will fix the cell parameters and only change the atom positions to its minimum energy structure (groud state structure).


4. How to make Supercell for Quantum ESPRESSO