<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV><DIV>On Apr 19, 2006, at 3:35 AM, 针叶 朱 wrote:</DIV><BR class="Apple-interchange-newline"><BLOCKQUOTE type="cite"><DIV>Dear stefano Baroni:</DIV> <DIV>i want to caculate the properties of SrTiO3 under tensile strain. i have known the crystal structure of SrTiO3 under tensile strain is Amm2 space group, and atomic cartesian cooridinate : Sr(0,0,0),Ti(<SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">(0.5+</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: 'Times New Roman'">Δ</SPAN><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">x,0,0.5),<SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">O1(0.5+</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: 'Times New Roman'">Δ</SPAN><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">x,0,0) O2(0.25+</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: 'Times New Roman'">Δ</SPAN><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">x,0.25+</SPAN><SPAN style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-bidi-font-family: 'Times New Roman'">Δ</SPAN><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">y,0.5).there is several question about atomic question.</SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">first, in ATOMIC_POSITION{alat}, is atomic cooridinates along cartesian cooridinate? <BR></SPAN></SPAN></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>YES atomic coordinates are cartesian for every option of the ATOMIC_POSITION control card, but "crystal"</DIV><DIV><BR><BLOCKQUOTE type="cite"><DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">second in ATOMIC_POSITION{crystal}, is atomic cooridinates along crystal axis of primitive unit cell cooridinate？for hobr and angstrom,the case is same to the alat?</SPAN></SPAN></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>I do not quite understand the question, in any case the "crystal" atomic coordinates are defined by the convention:</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>x(:) = \sum_j AT(:,j)*c(j),</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>where x(:) are the atomic (cartesian) coordinates, and AT(:,1), AT(:,2), AT(:,3) are the the basis vectors of the Bravais lattice with their own units (you usually specify AT giving "ibrav" and "celldm(:)", the latter in Bohr radii). A list of conventional basis vectors used by PWscf (as well as much other useful information) is found in the documentation files distributed with the code (INPUT_PW, in the present case). Beware, though, that you hardly need to pass atomic positions in crystal units. It is usually far easier to pass them in cartesian coordinates.</DIV><DIV><BR><BLOCKQUOTE type="cite"> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">from symmestry, The SrTiO3 cartesian cooridinate:</SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">Sr 0.000000 0.000000 0.000000<BR>Ti 0.500000 0.000000 0.500000<BR>O 0.500000 0.000000 0.000000<BR>O 0.250000 -0.250000 0.000000<BR>O 0.750000 -0.250000 0.500000<BR>O 0.750000 -0.250000 0.000000<BR>O 0.250000 -0.250000 0.500000</SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">but i found that the ion position in still after optimization. please tell me how to input structure of AMM2 SrTiO3?</SPAN></SPAN></DIV></BLOCKQUOTE><DIV><BR class="khtml-block-placeholder"></DIV>This is a more subtle question which I would invite you to think about carefully by yourself. </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Suppose you want to find the (stable) equilibrium position of a particle in a double potential well, say V(x)=(x^2-1)^2, and that you start your numerical search from x=0. The force acting on the particle at this position is zero by symmetry. So, any algorithm aiming at finding the zeroes of the force would keep the particle fixed at x=0. Does this imply that this is an equilibrim position? Does this imply that this a _stable_ equilibrium position? How would you use an algorithm which finds the zeroes of the force to find a stable equilibrium configuration in this case? What has this all to do with you problem? </DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Please, give a thought at these questions and revert to us with or without a solution to your problem.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV>Stefano B.</DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR class="khtml-block-placeholder"></DIV><DIV><BR><BLOCKQUOTE type="cite"> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">There is my inputfile of </SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">SrTIO3<BR>&CONTROL<BR> title='st'<BR> calculation='relax'<BR> restart_mode = 'from_scratch' ,<BR> outdir = 'tmp' ,<BR> pseudo_dir = '/home/zzy/pwscf/pseudo/' ,<BR> prefix = 'pst' ,<BR> forc_conv_thr=1.0D-4<BR> tstress = .true. ,<BR> tprnfor = .true. ,<BR>/<BR>&SYSTEM<BR> ibrav=9,<BR> celldm(1)=7.5,<BR> celldm(2)=1<BR> celldm(3)=0.955<BR> nat=7,<BR> ntyp=3,<BR> ecutwfc=50,<BR> ecutrho=450<BR>/<BR>&ELECTRONS<BR> conv_thr=1.0d-6<BR>/<BR>&IONS<BR> ion_dynamics = 'bfgs' ,<BR>/<BR>ATOMIC_SPECIES<BR> Sr 87.62000 038-Sr-ca-sp-vgrp.uspp.UPF<BR> Ti 47.88000 022-Ti-ca-sp-vgrp.uspp.UPF<BR> O 15.99960 008-O-ca--vgrp.uspp.UPF<BR>ATOMIC_POSITIONS {crystal}<BR>Sr 0 0 0 0 0 0<BR>Ti 0.5 0 0.5 1 0 0<BR>O 0.5 0 0 1 0 0<BR>O 0.25 -0.25 0.0 1 1 0<BR>O 0.75 -0.25 0.5 1 1 0<BR>O 0.25 -0.25 0.5 1 1 0<BR>O 0.75 -0.25 0 1 1 0<BR>K_POINTS {automatic}<BR>6 6 6 1 1 1<BR></SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"></SPAN></SPAN> </DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">Regards</SPAN></SPAN></DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"></SPAN></SPAN> </DIV> <DIV><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><SPAN lang="EN-US" style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"> zhuzhenye</SPAN></SPAN></DIV><P>__________________________________________________<BR>赶快注册雅虎超大容量免费邮箱?<BR><A href="http://cn.mail.yahoo.com">http://cn.mail.yahoo.com</A></P></BLOCKQUOTE></DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">---</SPAN></SPAN></SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">Stefano Baroni - SISSA</SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; "> </SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">&</SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; "> </SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">DEMOCRITOS National Simulation Center - Trieste</SPAN></SPAN></SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">[+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype)</SPAN></SPAN></SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; ; font-size: 12px; "><BR style="; font-size: 12px; "></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">Please, if possible, don't</SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; "> </SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">send me MS Word or PowerPoint attachments</SPAN></SPAN></SPAN></FONT></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; ">Why? See:</SPAN></SPAN></SPAN></FONT><FONT class="Apple-style-span" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;"><SPAN class="Apple-style-span" style="font-size: 12px; "><SPAN class="Apple-style-span" style="font-size: 12px; "> </SPAN></SPAN></SPAN></FONT><A href="http://www.gnu.org/philosophy/no-word-attachments.html"><FONT class="Apple-style-span" color="#0023E9" size="3"><SPAN class="Apple-style-span" style="font-size: 12px;; color: rgb(0, 35, 233); -khtml-text-decorations-in-effect: underline; "><SPAN class="Apple-style-span" style="color: rgb(0, 35, 233); font-size: 12px; -khtml-text-decorations-in-effect: underline; "><SPAN class="Apple-style-span" style="color: rgb(0, 35, 233); font-size: 12px; -khtml-text-decorations-in-effect: underline; ">http://www.gnu.org/philosophy/no-word-attachments.html</SPAN></SPAN></SPAN></FONT></A></DIV><DIV><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN> </DIV><BR></BODY></HTML>