Dear all
I am attempting to simulate the adsorption of an N₂ molecule on a Na(100)
slab using QE. In my input file, I’m using a 12-layer Na 2x2 supercell with
a 15 Å vacuum gap. I have kept the interlayers fixed, allowing only the top
3 surface layers on both ends to relax, with an N₂ molecule on each surface
oriented perpendicular to the slab.
Additionally, I am using:
- The DFT-D3 van der Waals correction
- assume_isolated=2D to truncate interactions along the z-axis
- nspin=2 to allow for unconstrained polarization
The calculation has not yet converged, but it appears to be resulting in a
shortening of the N≡N bond, which is the opposite of what I expected.
Am I missing something here?
Thank you for any suggestions!
Sincerely,
Federico
Input file:
&CONTROL
calculation = 'relax'
etot_conv_thr = 1.0000000000d-04
forc_conv_thr = 1.0000000000d-03
outdir = ""
prefix = ""
pseudo_dir = "./SSSP_precision_pseudos"
verbosity = 'low'
restart_mode='from_scratch'
/
&SYSTEM
ibrav = 0
A = 8.30638
nat = 52
ntyp = 2
ecutrho = 385 ! *11
ecutwfc = 35
occupations = 'smearing'
smearing = 'gaussian'
degauss = 0.01
assume_isolated = '2D'
vdw_corr = 'dft-d3'
nspin = 2
starting_magnetization(1)= 0 ! Na
starting_magnetization(2)= 0.1 ! N
/
&ELECTRONS
conv_thr = 1.0000000000d-6 ! Default
electron_maxstep = 200
mixing_beta = 4.0000000000d-01
/
&IONS
ion_dynamics = 'bfgs'
/
CELL_PARAMETERS {alat}
1.000000000000000 0.000000000000000 0.000000000000000
0.000000000000000 1.000000000000000 0.000000000000000
0.000000000000000 0.000000000000000 4.683585508970213
ATOMIC_SPECIES
Na 22.98900 Na.paw.z_9.ld1.psl.v1.0.0-low.upf
N 14.00650 N.oncvpsp.upf
ATOMIC_POSITIONS {crystal}
Na 0.000000000000000 0.000000000000000 -0.000032000000000 1 1 1
Na 0.000000000000000 0.500000000000000 -0.000032000000000 1 1 1
Na 0.500000000000000 0.000000000000000 -0.000032000000000 1 1 1
Na 0.500000000000000 0.500000000000000 -0.000032000000000 1 1 1
Na 0.000000000000000 0.000000000000000 0.106684000000000 1 1 1
Na 0.000000000000000 0.500000000000000 0.106684000000000 1 1 1
Na 0.500000000000000 0.000000000000000 0.106684000000000 1 1 1
Na 0.500000000000000 0.500000000000000 0.106684000000000 1 1 1
Na 0.000000000000000 0.000000000000000 0.213377000000000 0 0 0
Na 0.000000000000000 0.500000000000000 0.213377000000000 0 0 0
Na 0.500000000000000 0.000000000000000 0.213377000000000 0 0 0
Na 0.500000000000000 0.500000000000000 0.213377000000000 0 0 0
Na 0.000000000000000 0.000000000000000 0.320068000000000 0 0 0
Na 0.000000000000000 0.500000000000000 0.320068000000000 0 0 0
Na 0.500000000000000 0.000000000000000 0.320068000000000 0 0 0
Na 0.500000000000000 0.500000000000000 0.320068000000000 0 0 0
Na 0.000000000000000 0.000000000000000 0.426760000000000 0 0 0
Na 0.000000000000000 0.500000000000000 0.426760000000000 0 0 0
Na 0.500000000000000 0.000000000000000 0.426760000000000 0 0 0
Na 0.500000000000000 0.500000000000000 0.426760000000000 0 0 0
Na 0.000000000000000 0.000000000000000 0.533446000000000 1 1 1
Na 0.000000000000000 0.500000000000000 0.533446000000000 1 1 1
Na 0.500000000000000 0.000000000000000 0.533446000000000 1 1 1
Na 0.500000000000000 0.500000000000000 0.533446000000000 1 1 1
Na 0.250000000000000 0.250000000000000 0.053371000000000 1 1 1
Na 0.250000000000000 0.750000000000000 0.053371000000000 1 1 1
Na 0.750000000000000 0.250000000000000 0.053371000000000 1 1 1
Na 0.750000000000000 0.750000000000000 0.053371000000000 1 1 1
Na 0.250000000000000 0.250000000000000 0.160012000000000 0 0 0
Na 0.250000000000000 0.750000000000000 0.160012000000000 0 0 0
Na 0.750000000000000 0.250000000000000 0.160012000000000 0 0 0
Na 0.750000000000000 0.750000000000000 0.160012000000000 0 0 0
Na 0.250000000000000 0.250000000000000 0.266740000000000 0 0 0
Na 0.250000000000000 0.750000000000000 0.266740000000000 0 0 0
Na 0.750000000000000 0.250000000000000 0.266740000000000 0 0 0
Na 0.750000000000000 0.750000000000000 0.266740000000000 0 0 0
Na 0.250000000000000 0.250000000000000 0.373399000000000 0 0 0
Na 0.250000000000000 0.750000000000000 0.373399000000000 0 0 0
Na 0.750000000000000 0.250000000000000 0.373399000000000 0 0 0
Na 0.750000000000000 0.750000000000000 0.373399000000000 0 0 0
Na 0.250000000000000 0.250000000000000 0.480132000000000 1 1 1
Na 0.250000000000000 0.750000000000000 0.480132000000000 1 1 1
Na 0.750000000000000 0.250000000000000 0.480132000000000 1 1 1
Na 0.750000000000000 0.750000000000000 0.480132000000000 1 1 1
Na 0.250000000000000 0.250000000000000 0.586794000000000 1 1 1
Na 0.250000000000000 0.750000000000000 0.586794000000000 1 1 1
Na 0.750000000000000 0.250000000000000 0.586794000000000 1 1 1
Na 0.750000000000000 0.750000000000000 0.586794000000000 1 1 1
N 0.500000000000000 0.250000000000000 0.638203000000000 1 1 1
N 0.500000000000000 0.250000000000000 0.667799000000000 1 1 1
N 0.250000000000000 0.000000000000000 0.948559000000000 1 1 1
N 0.250000000000000 0.000000000000000 0.918963000000000 1 1 1
K_POINTS automatic
7 7 1 0 0 0
--
*Federico Verdicchio *
*Ph.D. in Chemical Sciences*
*School of Science and Technology - Chemistry Division*
*Via S. Agostino, 1*
*62032 Camerino (MC)*
*Italy*
*Phone: +39 334 2758061*
--
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