The requirement I have is to calculate the bulk modulus from the Energy values at certain Volumes obtained via DFT calculations. Can you provide the instructions to use the ev.x tool in the Quantum ESPRESSO package ?.
Follow the steps provided below to execute the same :
- Prepare a text file with two columns, the first column being the unit cell volume (a.u^3 or Å^3 ) of each of your calculations, the second column being the corresponding total energy (Ry).
- Run the ‘ev.x’, which will ask you some questions.
- units : (a.u. 3 or Å 3 )
- the type of Bravais lattice: for fcc, bcc and sc lattices you have to specify the lattice > > parameter in your input text file, all other ‘noncubic’ lattices, this should be the volume
- The equation of state
It will give you in return the equilibrium volume(V0) and bulk modulus(K0) obtained from fitting a Birch- Murnaghan equation of state through your data points in a tabular form as given below.