<DIV>Hi Yanchistky and all Wien users,</DIV> <DIV>Thanks for your suggestion and sorry for late response. Actually in the mean time I have done my homework.</DIV> <DIV>I have generated ( 2 2 1 ) supercell with vacuum slab 4 bohr .At last, scf of the supercell is converged nicely by reducing Rkmax to 5.00.Space group of the supercell is !67 R-3c.</DIV> <DIV>But one more query,is the (2 2 1 )type supercell treatment (for Al2O3) correct or not ?</DIV> <DIV>The above same calculation with Rkmax 6.00,dstart is completed without any problem.But scf is ended after lapw0 in 1st cycle with an error message given below:</DIV> <DIV>forrtl:severe (174) : SIGSEGV,segmentation fault occured.</DIV> <DIV>Stack trace terminated abnormally.</DIV> <DIV>Added information: ( 2 2 2 ) supercell calculation is terminated in dstart step becoz of insufficient virtual memory problem. Total number of atoms in this supercell is 240.</DIV> <DIV>Please suggest me.</DIV> <DIV>Regards.</DIV>
<DIV>Swati<BR><BR><BR><BR><B><I>"B. Yanchitsky" <yan@im.imag.kiev.ua></I></B> wrote:</DIV> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">swati chaudhury wrote:<BR>> (i) For the hexagonal axes if I add 30 indivisual atoms (12-Al,18-O) the <BR>> space group is o.k.But in supercell ( 2 2 1 ,120 atoms) dstart is <BR>> not ending (symmetry 1).<BR>> (ii)Similarly if I put 12 positions against one Al and 18 positions <BR>> against one O, again space group is o.k but dstart gives ROTDEF error in <BR>> unit cell (12 symmetry generated, expected is 36).<BR>> What can I do next?<BR><BR>In general, once you have a created unit cell, you create a super cell with supercell,<BR>but the super cell file is raw, you have to introduce some symmetry break, for example,<BR>provide extra vacuum space, distort atoms from their positions, remove an atom to model<BR>a hole, add an impurity atom, etc....<BR>Next, you
have to set up the modified cell according to its symmetry. Try sgroup for that.<BR>If you still have problems on that, send me your structure files.<BR><BR>120 atoms cell is a big case, estimated matrix size would be near 12000x12000,<BR>with a lower symmetry, it might be difficult for calculations.<BR><BR>> unit cell (12 symmetry generated, expected is 36).<BR><BR>That's ok for 12 operations, for wien package 36 is wrong.<BR><BR>Regards,<BR><BR>Bogdan Yanchistky<BR><BR>Institute of Magnetism<BR>Vernadsky Blvd., 36-b<BR>03142 Kiev<BR>UKRAINE<BR><BR>Tel. (+380-44) 444 34 20<BR>Fax. (+380-44) 444 10 20<BR><BR><BR>_______________________________________________<BR>Wien mailing list<BR>Wien@zeus.theochem.tuwien.ac.at<BR>http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien<BR></BLOCKQUOTE><BR>