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i want to calculate elastic constant for a semiconductor compound what is the good way for this reason. I tried through elastic tutorial (Tutorespon) for calculating elastic constant of Aluminium metal, but i didn't get a good result, so any one have another method?
i have the structure parameter after optimation :
#Common input variables

#Definition of the unit cell
acell 3*4.6295 angstrom # This is equivalent to 10.61 10.61 10.61
rprim 0.0 0.5 0.5 # In tutorials 1 and 2, these primitive vectors
0.5 0.0 0.5 # (to be scaled by acell) were 1 0 0 0 1 0 0 0 1
0.5 0.5 0.0 # that is, the default.

#Definition of the atom types
ntypat 2 # There are two types of atom
znucl 30 8 # The keyword "znucl" refers to the atomic number of the
# possible type(s) of atom. The pseudopotential(s)
# mentioned in the "files" file must correspond
# to the type(s) of atom. Here, type 1 is the Aluminum,
# type 2 is the Arsenic.

#Definition of the atoms
natom 2 # There are two atoms
typat 1 2 # The first is of type 1 (Al), the second is of type 2 (As).

xred 0.0 0.0 0.0
0.25 0.25 0.25

#Gives the number of band, explicitely (do not take the default)
nband 10

#Exchange-correlation functional

ixc 11 # LDA Teter Pade parametrization

#Definition of the planewave basis set

ecut 40 # Maximal kinetic energy cut-off, in Hartree

#Definition of the k-point grid
ngkpt 4 4 4
nshiftk 4 # Use one copy of grid only (default)
shiftk 0.0 0.0 0.5 # This gives the usual fcc Monkhorst-Pack grid
0.0 0.5 0.0
0.5 0.0 0.0
0.5 0.5 0.5
So, can any one give me the input file final to calculate elastic constant

Hello houssem,

Since you already relaxed your structure, you should start your calculation using the input file "telastic_2.in" in the tutorial.

Once you replace the system dependent variables (rprim, acell, etc. ) the input file will work for the first step of the calculation. As I am sure you noticed in the tutorial https://docs.abinit.org/tutorial/elastic/index.html there are multiple steps to this calculation.

-Nick