Dear all,
I want to do an SCF calculation on sodalite (a kind of zeolite) unit cell (consisting 36 atoms) but I'm having some difficulties to do so. First off, I don't know what the vital and least parameters needed for these types of calculations are. So I used virtual nanolab to generate an input file. Following a tutorial on Quantum Wise website, I manipulated the input files, for instance they said to include nbnd=10, change the ecutwfc=30, etc.However, when I stared running the simulation, I kept getting an error "too few bands". So I started increasing the number by the order of 10 (without having any idea what it is!) and at nbnd=100 my simulations is now being run. I left other variables (such as K_POINTS) unchanged. I would really appreciate it if someone would tell me what should be and should not be in my input file for scf calculations and give me a sense of the range of numbers that I'm allowed to assign to the variables. Here is my input file: &control calculation = 'scf' verbosity = 'high' restart_mode = 'from_scratch' prefix = 'SOD' tstress = .false. tprnfor = .false. pseudo_dir = './' outdir = '/tmp' / &system ibrav=0 nat=36 ntyp=2 ecutwfc=30 ecutrho=300 nbnd=100 input_dft='PBE' / &electrons diagonalization='david' mixing_mode = 'plain' mixing_beta = 0.7 conv_thr = 1.0d-08 / ATOMIC_SPECIES O 15.999400 O.pbe-kjpaw.UPF Si 28.085500 Si.pbe-rrkj.UPF ATOMIC_POSITIONS bohr O 4.223852 10.209245 16.553687 O 12.694549 1.738548 8.082990 O 16.194639 10.209245 16.553687 O 7.723942 1.738548 8.082990 O 16.194639 10.209245 4.582900 O 7.723942 1.738548 13.053597 O 4.223852 10.209245 4.582900 O 12.694549 1.738548 13.053597 O 16.194639 4.223852 10.568293 O 7.723942 12.694549 19.038991 O 16.194639 16.194639 10.568293 O 7.723942 7.723942 2.097596 O 4.223852 16.194639 10.568293 O 12.694549 7.723942 2.097596 O 4.223852 4.223852 10.568293 O 12.694549 12.694549 2.097596 O 10.209245 16.194639 4.582900 O 1.738548 7.723942 13.053597 O 10.209245 16.194639 16.553687 O 1.738548 7.723942 8.082990 O 10.209245 4.223852 16.553687 O 1.738548 12.694549 8.082990 O 10.209245 4.223852 4.582900 O 1.738548 12.694549 13.053597 Si 5.973897 10.209245 19.038991 Si 14.444594 1.738548 10.568293 Si 14.444594 10.209245 2.097596 Si 5.973897 1.738548 10.568293 Si 1.738548 5.973897 10.568293 Si 10.209245 14.444594 19.038991 Si 1.738548 14.444594 10.568293 Si 10.209245 5.973897 2.097596 Si 10.209245 1.738548 6.332945 Si 1.738548 10.209245 14.803642 Si 10.209245 1.738548 14.803642 Si 1.738548 10.209245 6.332945 K_POINTS gamma CELL_PARAMETERS bohr 17.933187 0.000000 0.000000 0.000000 17.933187 0.000000 0.000000 0.000000 21.136587 Best regards, Amir M. Mofrad Graduate Research Assistant Chemical Engineering Department University of Missouri
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