Hello, I am trying to study the H/LiF(001) system, my first insulating surface. When I calculate the energy as a function of the H-LiF surface I obtain an odd shoulder around 5 bohr (see figure attached). I am considering an 8 layer slab, around 30 bohr of vacuum between slabs, a sqrt(2)xsqrt(2) surface cell, pbe rrkjus US pseudopotentials for all three elements with Li semicore electrons included. Is this behavior expected for an ionic insulating surface? Or is there a problem with my input file? I am setting:
&control prefix = 'F', outdir = '/home/myoutdir', pseudo_dir = '/home/mypseudo', calculation = 'scf', lkpoint_dir = .false., verbosity = 'high', nstep = 1, / &system ibrav = 8, celldm(1) = 7.6899999999999995, celldm(2) = 1.0000000000000000, celldm(3) = 7.5000000000000009, nat = 33, ntyp = 3, ecutwfc = 100, ecutrho = 500, occupations = 'smearing', smearing = 'gaussian', degauss = 0.0001, nspin = 2, starting_magnetization(1) = 0. starting_magnetization(2) = 0. starting_magnetization(3) = 1. / &electrons conv_thr = 1.d-6, diagonalization = 'cg', mixing_mode = 'plain', mixing_beta = 0.7D0, / ATOMIC_SPECIES F 18.9984032 F.pbe-n-rrkjus_psl.0.1.UPF Li 6.941 Li.pbe-s-rrkjus_psl.0.2.1.UPF H 1.00794 H.pbe-rrkjus_psl.0.1.UPF ATOMIC_POSITIONS crystal H 0 0 0.5013437 0 0 0 F 0.00 0.00 0.46666667 0 0 0 Li 0.50 0.00 0.46666667 0 0 0 Li 0.00 0.50 0.46666667 0 0 0 F 0.50 0.50 0.46666667 0 0 0 Li 0.00 0.00 0.40000000 0 0 0 F 0.50 0.00 0.40000000 0 0 0 F 0.00 0.50 0.40000000 0 0 0 Li 0.50 0.50 0.40000000 0 0 0 F 0.00 0.00 0.33333333 0 0 0 Li 0.50 0.00 0.33333333 0 0 0 Li 0.00 0.50 0.33333333 0 0 0 F 0.50 0.50 0.33333333 0 0 0 Li 0.00 0.00 0.26666667 0 0 0 F 0.50 0.00 0.26666667 0 0 0 F 0.00 0.50 0.26666667 0 0 0 Li 0.50 0.50 0.26666667 0 0 0 F 0.00 0.00 0.20000000 0 0 0 Li 0.50 0.00 0.20000000 0 0 0 Li 0.00 0.50 0.20000000 0 0 0 F 0.50 0.50 0.20000000 0 0 0 Li 0.00 0.00 0.13333333 0 0 0 F 0.50 0.00 0.13333333 0 0 0 F 0.00 0.50 0.13333333 0 0 0 Li 0.50 0.50 0.13333333 0 0 0 F 0.00 0.00 0.06666667 0 0 0 Li 0.50 0.00 0.06666667 0 0 0 Li 0.00 0.50 0.06666667 0 0 0 F 0.50 0.50 0.06666667 0 0 0 Li 0.00 0.00 0.00000000 0 0 0 F 0.50 0.00 0.00000000 0 0 0 F 0.00 0.50 0.00000000 0 0 0 Li 0.50 0.50 0.00000000 0 0 0 K_POINTS automatic 3 3 1 1 1 1 For testing purposes, I am using an unrelaxed LiF surface. Any help and/or suggestion will be greatly appreciated. I myself am quite at a loss...:-( Gisela. Surface Physics Group Centro At?mico Bariloche Argentina -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130610/ad002c80/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: test_EvsZ.png Type: image/png Size: 7743 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130610/ad002c80/attachment.png