Dear all,I have tried to perform vc-relax calculations with Quantum Espresso v6.0 using the XDM Van-der-Waals correction. I get some strange results, because it seems that the calculated XDM stress depends on the k-point parallelization. As a test I performed three scf calculations using the same input (see attached) just variing the number of k-point pools:
2 pools with 3 k-points: XDM stress (-33.37 -33.37 -40.79) 3 pools with 2 k-points: XDM stress (-58.75 -58.75 -61.19) 6 pools with 1 k-point: XDM stress (-117.51 -117.51 -122.37)The stress ratio 1: 1/2 : 1/3 is the inverse of the k-point ratio per pool... Has somebody seen something like this before?
Best regards, Malte -- Malte Sachs Anorganische Chemie, Fluorchemie Philipps-Universität Marburg Hans-Meerwein-Straße 4 35032 Marburg (Paketpost: 35043 Marburg) Tel.: +49 (0)6421 28 - 25 39 5 http://www.uni-marburg.de/fb15/ag-kraus/
&CONTROL
calculation = 'scf',
title = 'UCl6_P-3m1'
verbosity = 'high'
prefix = 'UCl6_P3'
outdir = './outdir/'
pseudo_dir = '/home/Sachsm/Promotion/Pseudos/'
tstress = .true.,
wf_collect = .true.
etot_conv_thr = 1.0D-8,
forc_conv_thr = 1.0D-6
/
&SYSTEM
ibrav = 4,
celldm(1) = 20.55532424,
celldm(3) = 0.461663392,
nat = 21,
ntyp = 2,
nbnd = 90,
occupations = 'fixed',
ecutwfc = 100,
ecutrho = 800,
vdw_corr = 'xdm',
xdm_a1 = 0.6512,
xdm_a2 = 1.4633,
/
&ELECTRONS
mixing_beta = 0.4,
mixing_mode = 'plain',
conv_thr = 1.D-10,
/
&IONS
/
&CELL
/
K_POINTS (automatic)
2 2 4 0 0 0
<<attachment: malte_sachs.vcf>>
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