I am currently using Quantum ESPRESSO to determine the minimum distance where the interaction between two nickel atoms becomes minimal. To do so, I set up a cube with two nickel atoms inside, one located at the origin and the other one along the body diagonal. For each calculation, the other nickel atom becomes farther from the one at the origin by an increment (0.5 angstrom).

Here is the sample quantum espresso input file:

&control

calculation = 'scf',

restart_mode='from_scratch',

prefix = 'ni_sep',

outdir = './outdir',

pseudo_dir = '/GBRV',

verbosity='high',

/

&system

ibrav=1,

A=12.0,

nat=2, ntyp=1,

ecutwfc=90,

ecutrho=720,

occupations='smearing',

smearing='gaussian',

degauss=0.01,

nspin=2,

starting_magnetization(1)=0.3,

/

&electrons

electron_maxstep=300,

conv_thr=1D-9,

mixing_beta=0.7,

mixing_mode='TF',

/

ATOMIC_SPECIES

Ni 58.693 ni_pbe_v1.4.uspp.F.UPF

ATOMIC_POSITIONS {angstrom}

Ni 0.000000 0.000000 0.000000

Ni 3.464100 3.464100 3.464100

K_POINTS {automatic}

11 11 11 0 0 0

The problem is that the calculation runs more than 10 hours in my machine. I would like to ask for help in optimizing the input file. Thank you