Hey Paolo <http://www.mail-archive.com/search?l=pw_forum@pwscf.org&q=from:%22Paolo+Giannozzi%22> ,
The reason I chose such a ridiculously high screening parameter was to see the difference between my highest occupied and lowest unoccupied states. I was finding that regardless of whether the screening parameter was 0.0 all the way to 100, I'm getting the same band gap for silicon (0.61 eV). Thanks, Phil On 5 November 2015 at 09:02, Ref Fymz <reff...@gmail.com> wrote: > Dear pw_forum, > > > I am trying to use the HSE hybrid functional within quantum espresso, I > have an 8 atom cubic silicon cell, and I have converged my k-point grid, > q-point grid, and my wavefunction ecut. However, regardless of how much I > change my screening parameter (from 0.0 bohr^-1 all the way to 100 > bohr^-1), the difference between my lowest unoccupied and highest occupied > state remains about 0.61 eV, this points towards a problem. Can anybody > point me in the right direction? > > Also, when I do an scf run, I'm not getting the pressures / forces printed > in the file, despite asking for them, is this due to the density of my > k-point and q-point grid? > > The only other thing I can think it could be from is the ecutvcut / > x_gamma_extrapolation / exxdiv_treatment. Has anybody else used QE for > silicon successfully? > > My input looks like this; > > &control > prefix='silicon', > pseudo_dir = 'espresso/pseudo/', > outdir='./tmp' > tprnfor = .true. > tstress = .true. > restart_mode = 'from_scratch' > > / > &system > ibrav = 1, celldm(1) =10.327, nat= 8, ntyp= 1, > ecutwfc = 120, input_dft = 'hse' > nqx1 = 8, nqx2 = 8, nqx3 = 8 > nbnd = 32 > screening_parameter = 100 > occupations = 'fixed' > / > &electrons > diagonalization='cg' > conv_thr = 1.0e-9 > / > ATOMIC_SPECIES > Si 28.086 Si.pbe-mt_fhi.UPF > > ATOMIC_POSITIONS alat > Si 0.0 0.0 0.0 > Si 0.5 0.5 0.0 > Si 0.5 0.0 0.5 > Si 0.0 0.5 0.5 > Si 0.25 0.25 0.25 > Si 0.75 0.75 0.25 > Si 0.75 0.25 0.75 > Si 0.25 0.75 0.75 > > K_POINTS automatic > 24 24 24 0 0 0 > > > > Thanks, > > > Phil >
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