<div>Dear Eyvaz,</div>
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<div>Thank you for this instructions!</div>
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<div>I just tried the coordinates from NRL-weblink, and didnot find any problems as before.</div>
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<div>But i have another problem want to ask you , which is just a result that i wanna finish </div>
<div>Stefano's exercise assigned last mail.</div>
<div> </div>
<div>I just found that inversion symmetry would not found by pw.x code when the FFT grds are not compatable with fractional translation. Then, I tried to mannually set fft grid by nr1,nr2,nr3 .</div>
<div>Take$(espresso) /examples/example02/si.scf.in for example, when <strong>ecutwfc</strong> is 18.0Ry, the pw.x would found all Sym Ops, with smallest FFT grids (20,20,20). But when <strong>ecutwfc</strong> is set to 30.0Ry
with (30,30,30) fft grids default, the code gave ""warning: symmetry operation # N not allowed". According to mannual, this warning is mostly related to fractional translation incompatable with the fft grids. So, i tried to reset fft grid respectly with (36,36,36), (40,40,40),(60,60,60) and (54,54,54) , no such warning messages are given for the first 3 situation but same occurs for the last fft grids. I cannot understand this test results, since the userguide states that this warning is due to"
<strong>FFT grid dimension along that direction is not divisible respectively by 2 or by 3, the symmetry operation will not transform the FFT grid into itself</strong>" . Obviously, all grids dimension along x/y/z direction can be divided by 2 or 3.
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<div> My understanding is correct or not ? </div>
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<div>Regards,</div>
<div>Hai-Ping</div>
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<div> </div>
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<div><br><br> </div>
<div><span class="gmail_quote">On 8/24/06, <b class="gmail_sendername">Eyvaz Isaev</b> <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:eyvaz_isaev@yahoo.com" target="_blank">eyvaz_isaev@yahoo.com
</a>> wrote:</span>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">Hi,<br><br>> I just relaxed Anatase TiO2 with *ibrav= 7 , *<br>> then output gave that Only 8 symmetry Operations are
<br>> found.<br>Because of that your setup is not consistent.<br>Your lattice parameter is<br>7.1356*0.529177=3.7759954012, but 2 Oxygen atoms have<br>X-component (in units of alat) of 0.5.<br>You put 1.888, but, 1.888
is not equal<br>3.7759954012/2=1.8879977. So, they could not be<br>considered the same within 10^{-6} which is a default<br>mismatch (please correct me if I am wrong). For sure<br>you have to use 7 digits (after point) in such a kind
<br>specific cases, as c/a, b/a (and cosines, presumably).<br>Besides, your atomic positions are completely<br>different of these specified in<br><a onclick="return top.js.OpenExtLink(window,event,this)" href="http://cst-www.nrl.navy.mil/lattice/struk.xmol/c5.pos" target="_blank">
http://cst-www.nrl.navy.mil/lattice/struk.xmol/c5.pos </a><br>Please use lattice parameters and atomic coordinates<br>(in Angstrom) as they are in the link, and report what<br>happens.<br><br>I am not sure that it is a good idea to relax a well
<br>known structure if you have a problem with its <br>symmetry.<br><br>Bests,<br>Eyvaz.<br><br>> According to your mail, this structure should have<br>> 16 Symmetry Operations,<br>> so<br>> how can i obtain correct symmetry operations ?
<br>><br>> Input file is below , thank you in advance ! <br>><br>><br>> *&CONTROL<br>> title = 'TiO2' ,<br>> calculation = 'relax',<br>> verbosity = 'default',<br>> tprnfor = .true.,
<br>> outdir = '/home/haiping/tmp/', <br>> prefix = 'tio2-1',<br>> disk_io = 'default',<br>> nstep = 200,<br>> pseudo_dir =<br>> '/home/haiping/espresso/pseudo/',
<br>> /*<br>><br>> *&SYSTEM <br>> ibrav= 7,<br>> celldm(1)=7.1356,celldm(3)=2.51218,<br>> nat = 6 ,<br>> ntyp = 2 ,<br>> nbnd = 30 ,
<br>> ecutwfc = 30.0000000000,<br>> occupations = 'fixed' ,<br>> *<br>><br>> *&ELECTRONS<br>> electron_maxstep = 100,<br>> conv_thr = 1.0e-09,<br>> mixing_mode = 'plain' ,
<br>> startingpot = 'atomic' , <br>> startingwfc = 'atomic' ,<br>> mixing_beta = 0.300000000,<br>> mixing_ndim = 8,<br>> diagonalization = 'david_overlap' ,<br>> diago_david_ndim = 8,
<br>> /*<br>><br>> *&IONS <br>> ion_dynamics = 'bfgs',<br>> pot_extrapolation = 'first_order',<br>> wfc_extrapolation = 'first_order',*<br>><br>> */*<br>>
<br>> *O 15.999 O.pw91-van_ak.UPF <br>> Ti 47.867 Ti.pw91-nsp-van.UPF<br>> ATOMIC_POSITIONS angstrom<br>> Ti 0.000000000 0.000000000 0.000000000<br>> Ti 0.000000000 1.888000000 2.371500000
<br>> O 0.000000000 0.000000000 -1.983097630<br>> O 0.000000000 0.000000000 1.983097630<br>> O 0.000000000 1.888000000 0.387796645<br>> O 0.000000000 1.888000000 4.355203355
<br>> K_POINTS automatic<br>> 6 6 7 0 0 0 <br>> *<br>> *<br>><br>> * On 8/20/06, Eyvaz Isaev <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:eyvaz_isaev@yahoo.com" target="_blank">
eyvaz_isaev@yahoo.com</a>><br>> wrote:<br>> ><br>> > OK, let me hint more.<br>> ><br>> > Anatase has a Pearson symbol tI12 or space group <br>> > I4_1/amd. So, ibrav should be 7, but you have
<br>> chosen a<br>> > monoclinic lattice, i.e. ibrav=14. The space group<br>> has<br>> > 16 symmetry elements, but your choice after<br>> correcting <br>> > ecutrho gives only 4 symmetry elements .
<br>> ><br>> > Imagine FCC lattice and its conventional basis<br>> > vectors now. According to you now we have to put<br>> > ibrav=4 or 5. But ibrav=2 for FCC lattice. <br>> ><br>> > In addition, I also checked your input file via
<br>> > XCrysDen before I replied previously. Yes, there<br>> is no<br>> > problem with it, but a figure does not look like<br>> > anatase though you used nonzero ibrav. XcrysDen <br>> > usually replicates atomic positions if
<br>> ibrav.neq.0.<br>> > For example, if you put ibrav=0 for FCC cell and<br>> > specify conventional CELL_PARAMETERS you will find<br>> a<br>> > rhombohedron, but using ibrav=2 and default basis
<br>> > vectors you find a cubic cell.<br>> ><br>> > Bests,<br>> > Eyvaz.<br>> ><br>> ><br>> > --- lan haiping <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:lanhaiping@gmail.com" target="_blank">
lanhaiping@gmail.com</a>> wrote: <br>> ><br>> > > Dear Eyvaz,<br>> > > Thank you.<br>> > > I checked the strcuture again using XCRYSDEN,<br>> > > and found no problems related to the lattices.
<br>> > ><br>> > > Regards,<br>> > ><br>> > > Hai-Ping<br>> > ><br>> > ><br>> > ><br>> > > On 8/20/06, Eyvaz Isaev <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:eyvaz_isaev@yahoo.com" target="_blank">
eyvaz_isaev@yahoo.com </a>><br>> > > wrote:<br>> > > ><br>> > > > Hi,<br>> > > ><br>> > > > It seems your lattice choice is not correct.<br>> > > Please
<br>> > > > have a look at <br>> > > ><br>> <a onclick="return top.js.OpenExtLink(window,event,this)" href="http://cst-www.nrl.navy.mil/lattice/struk/c5.html" target="_blank">http://cst-www.nrl.navy.mil/lattice/struk/c5.html
</a><br>> > > ><br>> > > > Bests,<br>> > > > Eyvaz. <br>> > > ><br>> > > > --- lan haiping <<a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:lanhaiping@gmail.com" target="_blank">
lanhaiping@gmail.com</a>> wrote:<br>> > > ><br>> > > > > Dear All,<br>> > > > > I also have calculated gamma phonon <br>> frequencies<br>> > > of<br>> > > > > anatase TiO2 .
<br>> > > > > I run ph.x caculation after relaxing the<br>> > > structure,<br>> > > > > but 9 of 18 frequencies <br>> > > > > are minus.<br>> > > > ><br>
> > > > > Would you please give me some hints and<br>> help?<br>> > > > ><br>> > > > > input settings are below, thank you in <br>> advance !<br>> > > > ><br>
> > > > > *phonons of TiO2 at Gamma<br>> > > > > &inputph<br>> > > > > tr2_ph=1.0d-14,<br>> > > > > recover=.true., <br>> > > > > epsil=.true.,
<br>> > > > > prefix='tio2',<br>> > > > > fildyn='TiO2-gamma.dyn',<br>> > > > > outdir='/home/haiping/tmp/'<br>> > > > > / <br>> > > > > 0.0
0.0 0.0*<br>> > > > > **<br>> > > > > *Relaxing calculation input :*<br>> > > > > *&CONTROL<br>> > > > > title = 'TiO2' , <br>> > > > > calculation = 'relax',
<br>> > > > > verbosity = 'default',<br>> > > > > tprnfor = .true.,<br>> > > > > outdir = '/home/haiping/tmp/', <br>> > > > > prefix = 'tio2',
<br>> > > > > disk_io = 'default',<br>> > > > > nstep = 200,<br>> > > > > pseudo_dir =<br>> > > > > '/home/haiping/espresso/pseudo/',
<br>> > > > > /<br>> > > > > &SYSTEM<br>> > > > > ibrav= 14,<br>> > > > ><br>> > > > > <br>> celldm(1)=10.2856,celldm(2)=1.0
,celldm(3)=1.0,<br>> > > > ><br>> > > > > celldm(4)=-0.759357,celldm(5)=-0.759357,<br>> > > > > celldm(6)=0.518714<br>> > > > > nat = 6 ,
<br>> > > > > ntyp = 2 ,<br>> > > > > nbnd = 30 ,<br>> > > > > ecutwfc = 30.0000000000,<br>> > > > > ecutrho =
160.000,<br>> > > > > occupations = 'fixed' ,<br>> > > > > /<br>> > > > ><br>> > > > ><br>> > > > > &ELECTRONS<br>> > > > > electron_maxstep = 100,
<br>> > > > > conv_thr = 1.0e-07,<br>> > > > > mixing_mode = 'plain' ,<br>> > > > > startingpot = 'atomic' ,<br>> > > > > startingwfc = 'atomic' ,
<br>> > > > > mixing_beta = 0.300000000,<br>> > > > > mixing_ndim = 8,<br>> > > > > diagonalization = 'david_overlap' ,<br>> > > > > diago_david_ndim = 8,
<br>> > > > > /<br>><br>=== message truncated ===<br><br><br>__________________________________________________<br>Do You Yahoo!?<br>Tired of spam? Yahoo! Mail has the best spam protection around<br><a onclick="return top.js.OpenExtLink(window,event,this)" href="http://mail.yahoo.com/" target="_blank">
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