I am working on optimizing a Si/Ge interface using Quantum ESPRESSO, but I am facing issues with the optimization—it is not converging at all. I would appreciate any suggestions or insights to improve my input file or the overall approach.

This is my Input file:

&CONTROL

calculation = 'relax'

verbosity = 'high'

restart_mode = 'from_scratch'

tstress = .true.

tprnfor = .true.

outdir = './'

!etot_conv_thr = 1e-08

!forc_conv_thr = 1e-06

disk_io = 'none'

pseudo_dir = './'

/

&SYSTEM

ibrav = 0

ecutwfc = 45

ecutrho = 360

ntyp = 2

nat = 20

! occupations = 'smearing',

! smearing = 'm-p',

! degauss = 0.01,

/

&ELECTRONS

electron_maxstep = 999

conv_thr = 1e-10

mixing_beta = 0.3

/

&IONS

ion_dynamics = 'bfgs'

/

&CELL

!cell_dynamics = 'bfgs'

!press = 0.0

!press_conv_thr = 0.05

!cell_dofree = 'z'

/

ATOMIC_SPECIES

Si 28.09 Si.pbe-n-rrkjus_psl.1.0.0.UPF

Ge 72.63 ge_pbe_v1.4.uspp.F.UPF

K_POINTS automatic

6 6 1 0 0 0

CELL_PARAMETERS (angstrom)

5.5592782497 0.0000000000 0.0000000000

0.0000000000 5.5592782497 0.0000000000

0.0000000000 0.0000000000 25.000000000

ATOMIC_POSITIONS (angstrom)

Si 4.082777 4.082777 1.360926

Si 0.000000 2.721851 2.721851

Si 4.082777 1.360926 4.082777

Si 0.000000 0.000000 0.000000

Si 0.000000 0.000000 5.443702

Si 1.360926 4.082777 4.082777

Si 2.721851 2.721851 0.000000

Si 2.721851 2.721851 5.443702

Si 1.360926 1.360926 1.360926

Si 2.721851 0.000000 2.721851

Ge 0.000000 0.000000 9.837427

Ge 1.418714 1.418714 11.256141

Ge 0.000000 2.837427 7.000000

Ge 0.000000 2.837427 12.674854

Ge 1.418714 4.256141 8.418714

Ge 2.837427 0.000000 7.000000

Ge 2.837427 0.000000 12.674854

Ge 4.256141 1.418714 8.418714

Ge 2.837427 2.837427 9.837427

Ge 4.256141 4.256141 11.256141