> ATOMIC_POSITIONS crystal > H 0.000000000 0.000000000 3.250000000 > C 0.000000000 0.000000000 0.000000000 > C 0.333333333 0.666666666 0.000000000 > C 0.000000000 0.000000000 0.500000000
You have an odd number N of electrons per unit cell, so your system IS metallic, and one cannot simply occupy the lowest N/2 bands as would be the default for an insulator. Hence you have to specify how to fill the electron bands. See file Doc/INPUT_PW, variables "occupation", "degauss", "smearing" and references given there for details. [If you want to think more about that, consider an H atom in a large box, suitable for an isolated-atom calculation. Then you have 1 electron per unit cell, which is odd again, so the system made of the repeated H atoms far away the one from the other is metallic, and you will find with PWscf that the lowest energy is given by half-filling a band which is nothing more than the (bonding) combination of the 1s orbitals, as it should be. Moreover, the results will not be much affected by the values you choose for the variables specified above. Can you imagine why?] Hope this helps, Guido Guido Fratesi Dipartimento di Fisica Universita` degli studi di Milano Via Celoria, 16 - 20133 MI (Italy)
