[QE-users] Why is my ev.x gave wrong calculations of equilibrium volume?

[Abdeslam Houari]

The equilibrium volume V0 given by the code is for the unit cell (per formula unit)The one you give, call it V, is the volume of the conventional cubic cell (V =4 * V0 )I hope it's clear !

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Abdesalem HOUARI
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Department of physics, Theoretical Physics Laboratory
University of Bejaia-06000. Algeria.
E-mail: abdeslam.houari at univ-bejaia.dz & habdslam at yahoo.fr
https://sites.google.com/site/houariabdeslam/homepage
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    On Wednesday, 22 February 2023, 12:59:54 pm GMT+1, Stefano Baroni <baroni at sissa.it> wrote:  
 
 There is nothing wrong in the result. It’s your expectations that are wrong. Divide your expected volume by the value given the code and explain why … SB

--Stefano Baroni, Trieste -- swift message written and sent on the go

Il giorno 22 feb 2023, alle ore 12:37, NAIMI SALMA <salma_naimi at um5.ac.ma> ha scritto:



I used ev.x tool to get the equation of state of my zincblende material by using an input file that contains a column of lattice parameters and a second column of the  corresponding total energies.
In the obtained output file the equilibruim lattice parameter a0 =  6.09174 Ang and the equilibruim volume V0 =   56.51 A^3 . And that`s wrong because the equilibruim volume should be V0 =  6.09174^3 = 226.060184202 A^3 .
You can find attached the output file of my Birch-Murnaghen equation and the way that I followed to respond to the questions when running ev.x.

Can you clarify my doubts, please! Thank you




Salma NAIMIPhD student-Mohamed 5 University-Rabat
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