You’re using ibrav=2, which corresponds to a cubic F (fcc). The atomic positions are in alat units. As such, as clearly stated by the error message, atoms 1 and 2 are equivalent. Indeed, their positions are: #1 --> a/2 a/2 0 #2 —> 0 0 0
Atom #1 lies at the center of a face, its position for a cubic bcc lattice is obtained by translating the lattice site at the origin (where atom #2 lies) by a direct lattice vector. You must specify *ONLY* inequivalent atoms, their periodic replicas cannot be included in the list of atoms. There are many other similar overlapping atoms, such as Ca —> 0 0 0 with Ca —> 1 1 0 or Ca —> 0 0 1. Actually, to be honest, you should probably remove *ALL ATOMS BUT TWO*. Indeed, as far as I remember, CaO has a cubic bcc lattice with on Ca atom in 0 0 0 and on O atom in a/2 a/2 a/2 (but please check!). Provided that, in my opinion, any question is welcome, my suggestion is that you try to give a solution to error messages by yourself before asking people, because what you learn if you “try to solve” is priceless if compared to what you learn if you “ask to solve”. In this respect, Quantum-ESPRESSO is an exceptional lab to make experience, since especially (but not only) for the easiest tasks (such as build the band structure of simple solids) many error messages are self-explanatory and user-friendly! ;-) Giovanni > On 17 Dec 2019, at 10:25, Pooja Vyas <[email protected]> wrote: > > Following is my input file. I obtained the atomic position using X-CrysDen. > But when I run the file it shows me an error message. > > Input file: > &control > calculation = 'scf', > prefix = '9.1334' > tstress= .true. > tprnfor= .true. > outdir = '/home/userpooja/cao.oct/' > pseudo_dir = '/home/userpooja/cao.oct/pseudo/' > / > &system > ibrav = 2, > celldm(1) = 9.1334, > nat = 27, > ntyp = 2, > ecutwfc = 100, > / > &electrons > mixing_beta = 0.7 > / > > ATOMIC_SPECIES > > Ca 40.078 Ca.pbe-nsp-van.UPF > O 15.999 O.pbe-van_ak.UPF > > ATOMIC_POSITIONS (alat) > Ca 0.5 0.5 0.0 > Ca 0.0 0.0 0.0 > Ca 0.5 0.0 0.5 > Ca 0.0 0.5 0.5 > O 0.0 0.0 0.5 > O 0.5 0.5 0.5 > O 0.0 0.5 0.0 > O 0.5 0.0 0.0 > Ca 0.5 0.5 1.0 > Ca 0.0 0.0 1.0 > O 0.0 0.5 1.0 > O 0.5 0.0 1.0 > Ca 0.0 1.0 0.0 > Ca 0.5 1.0 0.5 > O 0.0 1.0 0.5 > O 0.5 1.0 0.0 > Ca 0.0 1.0 1.0 > O 0.5 1.0 1.0 > Ca 1.0 0.0 0.0 > Ca 1.0 0.5 0.5 > O 1.0 0.0 0.5 > O 1.0 0.5 0.0 > Ca 1.0 0.0 1.0 > O 1.0 0.5 1.0 > Ca 1.0 1.0 0.0 > O 1.0 1.0 0.5 > Ca 1.0 1.0 1.0 > K_POINTS (automatic) > 11 11 11 1 1 1 > > Error: > > > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > task # 17 > from check_atoms : error # 1 > atoms # 1 and # 2 differ by lattice vector (-1, 1, 0) in crystal axis > > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users -- Giovanni Cantele, PhD CNR-SPIN c/o Dipartimento di Fisica Universita' di Napoli "Federico II" Complesso Universitario M. S. Angelo - Ed. 6 Via Cintia, I-80126, Napoli, Italy e-mail: [email protected] [email protected] Phone: +39 081 676910 Skype contact: giocan74 Web page: https://sites.google.com/view/giovanni-cantele
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