[Pw_forum] Partial density of states for bimetallic systems

[Sven Heiles]

Dear Quantum Espresso users.

I use QE 4.2.1 and have calculated the partial density of states (pDOS) 
for small bimetallic AuAg Clusters. For the calculations I typically 
placed the clusters in a cubic box of (cluster radius + 16) AA, with 50 
Ry energy cutoff (500 Ry density cutoff) and used Au.pbe-nd-rrkjus.UPF 
and Ag.pbe-d-rrkjus.UPF. After geometry optimization
I use projwfc.x to calculate pDOS.

For the pure systems and the silver rich clusters everythings looks 
fine. When I do the same calculations for gold rich clusters and compare 
the total DOS with the pDOS which is contributed from the Au and Ag 
atoms, respectively, I observe that the DOS form all Au atoms is higher 
than the total DOS (for some energies). I have observed this effect not 
only for one structure but for different isomers.

Below you can find sample input files and I can also attach the 
resulting DOS if this is needed. The geometry given in the input file is 
the optimized geometry.

Could this be due to a problem with the pseudo potentials used? Is it 
perhaps a problem that the two potentials use a different number of 
projected wavefunction (for Au s,p,d and for Ag s,d)?

Many thanks in advance

Best wishes

Sven

----------------------------------------------

&CONTROL
calculation = "relax",
prefix = "Au7Ag1_IV",
pseudo_dir = " . ",
outdir = "/scratch/xs/",
etot_conv_thr= 1.0D-5,
forc_conv_thr= 1.0D-4,
nstep = 500,
/
&SYSTEM
ibrav = 0,
nat = 8,
ntyp = 2,
ecutwfc = 50.D0,
ecutrho = 400.D0,
occupations = "smearing",
smearing = "mp",
degauss = 0.005,
/
&ELECTRONS
conv_thr = 1.D-8,
mixing_beta = 0.5D0,
/
&IONS
/
CELL_PARAMETERS cubic
35.12 0.00 0.00
0.00 35.12 0.00
0.00 0.00 35.12
ATOMIC_SPECIES
Au 196.97 Au.pbe-nd-rrkjus.UPF
Ag 107.87 Ag.pbe-d-rrkjus.UPF
ATOMIC_POSITIONS {bohr}
Au 16.406811577 13.541797257 20.987665926
Au 13.951505318 17.709867934 19.449786254
Ag 21.264908797 12.421983607 19.161370450
Au 16.077915882 21.005082800 16.003674339
Au 18.694668590 16.624463571 17.595854913
Au 20.667864709 19.918026413 14.276411488
Au 23.400513864 15.564390404 15.773691665
Au 11.463173665 21.793220893 17.973137265
K_POINTS {Gamma}

--------------------------------------------------------------------------

&inputpp
outdir="/scratch/xs/"
prefix="Au7Ag1_IV"
io_choice="both"
/

-- 
Dipl. Ing. Sven Heiles
Technische Universität Darmstadt
AK Schäfer
Eduard-Zintl-Institut
Petersenstraße 20
D-64287 Darmstadt – Germany

Phone: ++49-(0)6151-164397
Fax: ++49-(0)6151-166024
Web: http://www.tu-darmstadt.de/fb/ch/cluster/schaefer.tud