<p style="margin: 0px; padding: 0px;">Dear Monish,</p><p style="margin: 0px; padding: 0px;"> thanks a lot for the prompt and exhaustive reply. I was wondering that I took an experimental geometry for both WZ and ZB, thus I was thinking that performing a simple "scf" calculation should have reproduce the experimental trend.</p><p style="margin: 0px; padding: 0px;"><br></p><p style="margin: 0px; padding: 0px;">Thanks a lot!</p><p style="margin: 0px; padding: 0px;">With best regards,</p><p style="margin: 0px; padding: 0px;">Giacomo<br></p><p style="margin: 0px; padding: 0px;"><br></p><p style="margin: 0px; padding: 0px;"><br></p><p style="margin: 0px; padding: 0px;"><br></p>
<blockquote>
----Messaggio originale----<br>
Da: mohnish.iitk@gmail.com<br>
Data: 29/02/2012 4.37<br>
A: "giacsport@libero.it"<giacsport@libero.it><br>
Ogg: Re: [Pw_forum] WZ and ZB ZnO<br>
<br>
Dear Giacomo,<br><br>Are you sure that you optimized the structure with "calculation" = "vc-relax" flag? I mean after the optimization the forces and stress should be below the threshold value. And I use PBE ultrasoft pseudopotential and it worked pretty well for me. Below are the inputs attached : By the way the "nspin" flag that you are using needs finite starting magnetization for atleast one species otherwise it wont do the spin polarized calculation. Feel free to ask any further doubt you have.<br>
<br><b>Wurtzite:</b><br><br> &control<br> calculation = 'vc-relax',<br> restart_mode='restart',<br> nstep=300<br> outdir='/home/rajpala/Desktop/zno-wur',<br> pseudo_dir='/home/rajpala/Desktop/zno-wur'<br>
prefix='zno',<br> tstress = .true.,<br> tprnfor = .true.,<br> /<br> &system <br> ibrav= 4, a = 3.25, c = 5.25,nat= 4, ntyp= 2,<br> ecutwfc = 35,ecutrho=280,occupations='smearing',degauss=0.01,smearing='gaussian' <br>
/<br> &electrons<br> diagonalization='david'<br> mixing_mode = 'plain'<br> mixing_beta = 0.7<br> conv_thr = 1.0d-8<br> /<br>&IONS<br> ion_dynamics='bfgs'<br> trust_radius_min=1.D-7<br>
/<br> &CELL<br> cell_dynamics='bfgs'<br>/<br>ATOMIC_SPECIES<br> Zn 65.390 Zn.pbe-van.UPF<br> O 15.099 O.pbe-rrkjus.UPF<br> ATOMIC_POSITIONS (crystal)<br> Zn 0.000000000000 0.0000000000 0.00000000000 <br>
Zn 0.333333333333 0.6666666667 0.50000000000 <br> O 0.000000000000 0.0000000000 0.34500000000<br> O 0.333333333333 0.6666666667 0.84500000000 <br> K_POINTS (automatic)<br> 8 8 6 0 0 0<br><br><b><i>Final enthalpy = -317.1024506964 Ry = -158.551225348 Ry/formula unit. </i></b><br>
<br><b>Zincblende :</b><br><br>&control<br> calculation = 'vc-relax'<br> prefix='zno'<br> tstress = .true.<br> tprnfor = .true.<br> outdir="/home/rajpala/Desktop/zno-zincblend-bulk"<br>
pseudo_dir="/home/rajpala/Desktop/zno-zincblend-bulk"<br> /<br> &system <br> ibrav= 2, a =4.60,nat= 2, ntyp= 2,ecutwfc = 40,ecutrho =320, occupations='smearing',degauss=0.01,smearing='gaussian' <br>
/<br> &electrons<br> diagonalization='david'<br> mixing_mode = 'plain'<br> mixing_beta = 0.7<br> conv_thr = 1.0d-8<br> /<br>&IONS<br> ion_dynamics='bfgs'<br>/<br> &CELL<br> cell_dynamics='bfgs'<br>
/<br>ATOMIC_SPECIES<br> Zn 65.390 Zn.pbe-van.UPF<br> O 15.099 O.pbe-rrkjus.UPF<br>ATOMIC_POSITIONS (crystal)<br> Zn 0.00 0.00 0.00 <br> O 0.25 0.25 0.25<br>K_POINTS (automatic)<br> 6 6 6 0 0 0<br><br><b><i>Final enthalpy = -158.5504170143 Ry/formula unit</i></b><br>
<br><div class="gmail_quote">On Wed, Feb 29, 2012 at 8:31 AM, <a href="mailto:giacsport@libero.it" mce_href="mailto:giacsport@libero.it">giacsport@libero.it</a> <span dir="ltr"><<a href="mailto:giacsport@libero.it" mce_href="mailto:giacsport@libero.it">giacsport@libero.it</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex" mce_style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid #cccccc;padding-left:1ex"><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Dear all,</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"> regardless the pseudopotentials I use for my optimization and the kpoint sampling, I always obtain that ZB phase of ZnO is (slightly) more stable than WZ.</p>
<p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Since I would like to make HSE calculations on such systems I would like to have an already well-ordered (in terms of energy, of course) structures at PBE level. (In my case WZ and ZB look almost degenerate, but always with ZB slightly more stable than WZ)<br>
</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Can anyone help me to refine parameters that allow me to obtain E WZ < E ZB. Here you find the two inputs.</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">
<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Wurtzite ZnO</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">&CONTROL<br> calculation = "scf"<br> pseudo_dir = './'<br> outdir='./',<br> restart_mode="from_scratch",<br>
prefix='ZnO_WZ',<br> tprnfor = .true.,<br> tstress = .true.,<br> wf_collect=.true.,<br>/<br>&SYSTEM<br> ibrav= 4, celldm(1) =6.13821, celldm(3)=1.6023951, nat= 4, ntyp= 2,<br> ecutwfc =90.0, nbnd = 80, nspin=2, tot_magnetization=0,<br>
/<br>&ELECTRONS<br> diagonalization='david'<br> mixing_mode = 'plain'<br> mixing_beta = 0.7<br> conv_thr = 1.0d-8<br>/<br>ATOMIC_SPECIES<br> Zn 65.38 Zn-GGA-pbe.fhi.UPF<br> O 15.9994 O-GGA-pbe.fhi.UPF<br>
ATOMIC_POSITIONS (crystal)<br> Zn 0.33333 0.66667 0.00000<br> Zn 0.66667 0.33333 0.50000<br> O 0.33333 0.66667 0.38210<br> O 0.66667 0.33333 0.88210<br>K_POINTS (automatic)<br>12 12 9 0 0 0<br>
</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">total energy = -285.55060915 Ry/2 = -142.7753045750<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">
<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Zincblende ZnO</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">&control<br> calculation = 'scf'<br> restart_mode='from_scratch',<br>
prefix='ZnO_ZB',<br> tprnfor = .true.,<br> tstress = .true.,<br> wf_collect=.true.,<br> pseudo_dir='./',<br> outdir='./',<br>/<br>&system<br> ibrav= 1, celldm(1) =8.730534067<br>
nat= 8, ntyp= 2,<br> ecutwfc =90., nbnd = 100, nspin=2, tot_magnetization=0<br>/<br>&electrons<br> diagonalization='david'<br> mixing_mode = 'plain'<br> mixing_beta = 0.7<br> conv_thr = 1.0d-8<br>
/<br>ATOMIC_SPECIES<br> Zn 65.38 Zn-GGA-pbe.fhi.UPF<br> O 15.9994 O-GGA-pbe.fhi.UPF<br>ATOMIC_POSITIONS (crystal)<br>Zn 0.00000 0.00000 0.00000<br>Zn 0.00000 0.50000 0.50000<br>Zn 0.50000 0.00000 0.50000<br>
Zn 0.50000 0.50000 0.00000<br>O 0.25000 0.25000 0.25000<br>O 0.25000 0.75000 0.75000<br>O 0.75000 0.75000 0.25000<br>O 0.75000 0.25000 0.75000<br>K_POINTS automatic<br>8 8 8 0 0 0<br>
</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">total energy = -571.10793352 Ry/4 = -142.776983375<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">
<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Thanks in advance for your help!</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Very best,</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">Giacomo</p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px">
<br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><tt>-- <br>
***************************************<br>
Giacomo Giorgi, Ph.D.<br>
<br>
Yamashita & Ushiyama Laboratory,<br>
Department of Chemical System Engineering,<br>
Faculty of Engineering,<br>
The University of Tokyo.<br>
<br>
tel&fax: +81-3-5841-7286<br>
email: <a>giacomo@tcl.t.u-tokyo.ac.jp</a><br>
HP: <a href="http://www.tcl.t.u-tokyo.ac.jp/" mce_href="http://www.tcl.t.u-tokyo.ac.jp/" target="_blank">http://www.tcl.t.u-tokyo.ac.jp/</a><br>
***************************************</tt></p><p style="margin:0px;padding:0px" mce_style="margin:0px;padding:0px"><br></p><div style="width:1px;min-height:1px;overflow:hidden"> </div><br>_______________________________________________<br>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Regards,<br>MOHNISH,<br>-----------------------------------------------------------------<br>Mohnish Pandey<div>BTech-Mtech, IIT Kanpur<br>Senior Project Associate,<br>
Department of Chemical Engineering,<br>IIT KANPUR, UP, INDIA<br>-----------------------------------------------------------------</div><br>
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</blockquote><p><br></p>