how to use ev.x for orthorhombic structure,where you have three input files corresponding to three lattice parameter variations.
Regards
Hi. For the case of orthorhombic structures where you create as you say three input files (each one varying a,b,c), just take the resulting volumes of each input file and also the total energies. Then create an .in (with the emacs command, for example) where your first column is the unit-cell volume (in u.a^3) and the second the total energy (in Ry, for example). Then load it in QE and use the ev.x command as shown in the example:
#comments
ev.x
Lattice parameter or Volume are in (au, Ang) > au #You are asked for the units
Enter type of bravais lattice (fcc, bcc, sc, noncubic) > noncubic #Orthorhombic structure is noncubic
Enter type of equation of state :
1=birch1, 2=birch2, 3=keane, 4=murnaghan > 4 #depends on what you choose.
Input file > .in #enter your input with its name
Minimization succeeded
Output file > .out #you are asked to enter a name for your .out
Note: The following floating-point exceptions are signalling: IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
I hope I understood your question to answer it satisfactorily.