<div dir="ltr">Hi, Vega:<br><br>A recent result (Jpn. J. Appl. Phys. 39 (2000) L847) showed that different pseudopotential leaded to different conclusions. <br><br>Best,<br><br>Wei<br><br><div class="gmail_quote">On Thu, Aug 28, 2008 at 4:28 AM, vega <span dir="ltr"><<a href="mailto:vegalew@hotmail.com">vegalew@hotmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="padding-right: 10px; padding-left: 10px; padding-top: 15px;" bgcolor="#ffffff" name="Compose message area">
<div><font size="2" face="Arial">Dear all,</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">It is known that the rutile is more stable than
anatase in thermodynamics. Surprisingly, when I did the vc-relax calculation by
QE, I found the calculated energy of anatase lower than
rutile. Both vc-relax calculation for rutile and anatase onverged in 6 scf
cycles and 3 bfgs steps, giving the final enthalpy = -362.7585836890 Ry for
rutile and -725.5447425835 Ry for antase. So the average energy of [TiO2] unit
is -181.3792918445 Ry for rutile and -181.386185645875 Ry for anatase. It
looks like anatase is more stable than rutile. Do you think it was quite
strange?</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">To make the calculation both for anatase and rutile
comparable, I used the same ecutwfc=40 Ry and ecutwfc=400 Ry, and a quite dense
k-point mesh for both case, 4x4x7 for rutile and 5x5x2 for anatase.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">for better understanding in my calculation, please
read the input file below,</font></div>
<div><font size="2" face="Arial">for anatase case,</font></div>
<div><font size="2" face="Arial">&CONTROL<br>
title = 'Anatase lattice'
,<br>
calculation = 'vc-relax'
,<br>
restart_mode = 'from_scratch'
,<br>
outdir = '/home/hjfeng/vega/TiO2/Anatase/lattice/vctest/tmp/'
,<br>
wfcdir = '/tmp/'
,<br>
pseudo_dir = '/home/hjfeng/vega/espresso-4.0/pseudo/'
,<br>
prefix = 'Anatase lattice'
,<br>
disk_io = 'none'
,<br>
nstep = 1000
,<br> /<br> &SYSTEM<br>
ibrav =
6,<br>
celldm(1) =
7.1356,<br>
celldm(3) =
2.5122,<br>
nat =
12,<br>
ntyp =
2,<br>
ecutwfc = 40
,<br>
ecutrho = 400 ,<br> /<br> &ELECTRONS</font></div>
<div> </div>
<div><font size="2" face="Arial"> /<br> &IONS<br>
ion_dynamics = 'bfgs'
,<br> /<br> &CELL<br>
cell_dynamics = 'bfgs' ,<br> /<br>ATOMIC_SPECIES<br>
Ti 47.86700 Ti.pw91-sp-van_ak.UPF <br>
O 15.99940 O.pw91-van_ak.UPF <br>ATOMIC_POSITIONS crystal
<br> Ti 0.000000000
0.000000000 0.000000000 <br>
Ti 0.500000000
0.500000000 0.500000000 <br>
Ti 0.000000000
0.500000000 0.250000000 <br>
Ti 0.500000000
0.000000000 0.750000000
<br> O
0.000000000 0.500000000
0.042000000 <br>
O 0.000000000
0.000000000 0.208000000
<br> O
0.500000000 0.500000000
0.292000000 <br>
O 0.000000000
0.500000000 0.458000000
<br> O
0.500000000 0.000000000
0.542000000 <br>
O 0.500000000
0.500000000 0.708000000
<br> O
0.000000000 0.000000000
0.792000000 <br>
O 0.500000000
1.000000000 0.958000000 <br>K_POINTS
automatic <br> 5 5 2 1 1 1 </font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">for rutile case,</font></div>
<div><font size="2" face="Arial"></font> </div>
<div> &CONTROL<br>
title = Rutile_lattice
,<br>
calculation = 'vc-relax'
,<br>
restart_mode = 'from_scratch'
,<br>
outdir = '/home/vega32/TiO2/rutile/lattice/vcrelax/tmp'
,<br>
wfcdir = '/tmp/'
,<br>
pseudo_dir = '/home/vega32/espresso-4.0.1/pseudo/'
,<br>
prefix = 'Anatase lattice'
,<br>
disk_io = 'none'
,<br>
nstep = 1000
,<br> /<br> &SYSTEM<br>
ibrav =
6,<br>
celldm(1) =
8.6814,<br>
celldm(3) =
0.6441,<br>
nat =
6,<br>
ntyp =
2,<br>
ecutwfc = 40
,<br>
ecutrho = 400 ,<br> /<br> &ELECTRONS</div>
<div> </div>
<div> /<br> &IONS<br>
ion_dynamics = 'bfgs'
,<br> /<br> &CELL<br>
cell_dynamics = 'bfgs' ,<br> /<br>ATOMIC_SPECIES<br>
O 15.99940 O.pw91-van_ak.UPF<br> Ti
47.90000 Ti.pw91-sp-van_ak.UPF<br>ATOMIC_POSITIONS
crystal <br> O
0.304800000 0.304800000
0.000000000 <br>
O 0.695200000
0.695200000 0.000000000
<br> O
0.195200000 0.804800000
0.500000000 <br>
O 0.804800000
0.195200000 0.500000000 <br>
Ti 0.500000000
0.500000000 0.500000000 <br>
Ti 0.000000000
0.000000000 0.000000000 <br>K_POINTS
automatic <br> 4 4 7 1 1 1 </div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">vega</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">==============================================================<br><font color="#888888">Vega
Lew ( weijia liu)<br>PH.D Candidate in Chemical Engineering<br>State Key
Laboratory of Materials-oriented Chemical Engineering<br>College of Chemistry
and Chemical Engineering<br>Nanjing University of Technology, 210009, Nanjing,
Jiangsu, China</font></font></div></div>
<br>_______________________________________________<br>
Pw_forum mailing list<br>
<a href="mailto:Pw_forum@pwscf.org">Pw_forum@pwscf.org</a><br>
<a href="http://www.democritos.it/mailman/listinfo/pw_forum" target="_blank">http://www.democritos.it/mailman/listinfo/pw_forum</a><br>
<br></blockquote></div><br></div>