According to your input information, nat=48, I think you wanted to make 2x2x2 rutile-TiO2 supercell with a substitutional Nb. However, you setted celldm(1) and ATOMIC_POSITIONS wrong. You may set celldm(1)=1 and keep CELL_PARAMETERS; or keep celldm(1)=8.7 and set CELL_PARAMETERS as 2.000 0.000 0.000 0.000 2.000 0.000 0.000 0.000 1.288 For ATOMIC_POSITIONS, you may set it as: ATOMIC_POSITIONS {crystal} O 0.1523998693948630 0.1523998693948630 0.0000000000000000 O 0.3476001306051368 0.3476001306051368 0.0000000000000000 O 0.0976001306051369 0.4023998693948629 0.2500000000000001 O 0.4023998693948629 0.0976001306051369 0.2500000000000001 O 0.6523998693948631 0.1523998693948630 0.0000000000000000 O 0.8476001306051368 0.3476001306051368 0.0000000000000000 O 0.5976001306051370 0.4023998693948629 0.2500000000000001 O 0.9023998693948629 0.0976001306051369 0.2500000000000001 O 0.1523998693948630 0.6523998693948631 0.0000000000000000 O 0.3476001306051368 0.8476001306051368 0.0000000000000000 O 0.0976001306051369 0.9023998693948629 0.2500000000000001 O 0.4023998693948629 0.5976001306051370 0.2500000000000001 O 0.6523998693948631 0.6523998693948631 0.0000000000000000 O 0.8476001306051368 0.8476001306051368 0.0000000000000000 O 0.5976001306051370 0.9023998693948629 0.2500000000000001 O 0.9023998693948629 0.5976001306051370 0.2500000000000001 O 0.1523998693948630 0.1523998693948630 0.5000000000000000 O 0.3476001306051368 0.3476001306051368 0.5000000000000000 O 0.0976001306051369 0.4023998693948629 0.7500000000000001 O 0.4023998693948629 0.0976001306051369 0.7500000000000001 O 0.6523998693948631 0.1523998693948630 0.5000000000000000 O 0.8476001306051368 0.3476001306051368 0.5000000000000000 O 0.5976001306051370 0.4023998693948629 0.7500000000000001 O 0.9023998693948629 0.0976001306051369 0.7500000000000001 O 0.1523998693948630 0.6523998693948631 0.5000000000000000 O 0.3476001306051368 0.8476001306051368 0.5000000000000000 O 0.0976001306051369 0.9023998693948629 0.7500000000000001 O 0.4023998693948629 0.5976001306051370 0.7500000000000001 O 0.6523998693948631 0.6523998693948631 0.5000000000000000 O 0.8476001306051368 0.8476001306051368 0.5000000000000000 O 0.5976001306051370 0.9023998693948629 0.7500000000000001 O 0.9023998693948629 0.5976001306051370 0.7500000000000001 Ti -0.0000000000000000 -0.0000000000000000 0.0000000000000000 Ti 0.2499999999999998 0.2499999999999998 0.2500000000000001 Ti 0.5000000000000000 -0.0000000000000000 0.0000000000000000 Ti 0.7499999999999998 0.2499999999999998 0.2500000000000001 Ti -0.0000000000000000 0.5000000000000000 0.0000000000000000 Ti 0.2499999999999998 0.7499999999999998 0.2500000000000001 Ti 0.5000000000000000 0.5000000000000000 0.0000000000000000 Ti 0.7499999999999998 0.7499999999999998 0.2500000000000001 Ti -0.0000000000000000 -0.0000000000000000 0.5000000000000000 Ti 0.2499999999999998 0.2499999999999998 0.7500000000000001 Ti 0.5000000000000000 -0.0000000000000000 0.5000000000000000 Ti 0.7499999999999998 0.2499999999999998 0.7500000000000001 Ti -0.0000000000000000 0.5000000000000000 0.5000000000000000 Ti 0.2499999999999998 0.7499999999999998 0.7500000000000001 Ti 0.5000000000000000 0.5000000000000000 0.5000000000000000 Ti 0.7499999999999998 0.7499999999999998 0.7500000000000001
-- GAO Zhe CMC Lab, MSE, SNU, Seoul, S.Korea At 2011-09-07 20:22:30,"Winfred Mulwa" <mulwawinfred at yahoo.com> wrote: Dear all I have tried doing a vc-relax on the attached TiO2 rutile supercell, the calculations stop after a few minutes without giving any error. What might be the problem? -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110907/b844fe2f/attachment.htm