using ElaStic_Setup_ESPRESSO for wurzite ZnO scf.in, I am getting Bravais lattice: Orthorombic C bace-centred and wrong elastic constants.

My scf.in file is

&CONTROL

calculation = ‘scf’ ,

restart_mode = ‘from_scratch’ ,

pseudo_dir = ‘/home/chaitanya/qe-7.0/pseudo/’ ,

outdir=’./’,

tstress = .true. ,

tprnfor = .true. ,

/

&SYSTEM

ibrav = 4,

celldm(1) = 6.084917683,

celldm(3) = 1.614906832,

nat = 4,

ntyp = 2,

ecutwfc = 50 ,

ecutrho = 200 ,

occupations = “smearing” ,

degauss = 1.00000e-02 ,

smearing = “gaussian” ,

/

&ELECTRONS

conv_thr = 1.00000e-06 ,

startingpot = “atomic” ,

startingwfc = “atomic+random” ,

mixing_mode = ‘plain’ ,

mixing_beta = 0.7 ,

diagonalization = ‘david’ ,

/

ATOMIC_SPECIES

Zn 65.39000 Zn.pbesol-nc.UPF

O 15.99940 O.pbesol-nc.UPF

ATOMIC_POSITIONS crystal

Zn 0.333300000 0.666700000 0.000000000

Zn 0.666700000 0.333300000 0.500000000

O 0.333300000 0.666700000 0.375000000

O 0.666700000 0.333300000 0.875000000

K_POINTS automatic

4 4 2 0 0 0

output is

The output of ElaStic code

Today is Sun Jan 30 21:58:21 2022

Symmetry of the second-order elastic constant matrix in Voigt notation.

for, space group-number between 16 and 74, Orthorhombic structure.

C11 C12 C13 0 0 0

C12 C22 C23 0 0 0

C13 C23 C33 0 0 0

0 0 0 C44 0 0

0 0 0 0 C55 0

0 0 0 0 0 C66

Elastic constant (stiffness) matrix in GPa:

1363.9 486.7 43.0 0.0 0.0 0.0

486.7 107.9 -470.9 0.0 0.0 0.0

43.0 -470.9 -529.5 0.0 0.0 0.0

0.0 0.0 0.0 -149.8 0.0 0.0

0.0 0.0 0.0 0.0 26.8 0.0

0.0 0.0 0.0 0.0 0.0 71.0

Elastic compliance matrix in 1/GPa:

0.00101 -0.00086 0.00085 0.00000 0.00000 0.00000

-0.00086 0.00263 -0.00241 0.00000 0.00000 0.00000

0.00085 -0.00241 0.00033 0.00000 0.00000 0.00000

0.00000 0.00000 0.00000 -0.00668 0.00000 0.00000

0.00000 0.00000 0.00000 0.00000 0.03729 0.00000

0.00000 0.00000 0.00000 0.00000 0.00000 0.01409

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Voigt bulk modulus, B_V = 117.75 GPa

Voigt shear modulus, G_V = 48.51 GPa

Reuss bulk modulus, B_R = -1140.27 GPa

Reuss shear modulus, G_R = 93.92 GPa

Hill bulk modulus, B_H = -511.26 GPa

Hill shear modulus, G_H = 71.22 GPa

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Voigt Young modulus, E_V = 127.97 GPa

Voigt Poisson ratio, nu_V = 0.32

Reuss Young modulus, E_R = 289.73 GPa

Reuss Poisson ratio, nu_R = 0.54

Hill Young modulus, E_H = 224.06 GPa

Hill Poisson ratio, nu_H = 0.57

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Elastic Anisotropy in polycrystalline, AVR = -31.880 %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Eigenvalues of elastic constant (stiffness) matrix:

1536.9

219.6

-814.2

-149.8

26.8

71.0

Which are not in agreement with the reported values.

Regards

M Chaitanya Varma

Dept of Physics

GITAM University

India