[Pw_forum] Problem of bands data

Liping Yu lyu7 at ncsu.edu
Tue Jan 29 19:50:17 CET 2008

```lan haiping wrote:
>
>
> Dear All,
>
> I have performed a bands calculation on a carbon nanotube system (7,0).
> SCF and NSCF calculations are well converged, but the bands data
> obtained from bands.x is very strange.
> I then checked the bands data between the output of nscf calculation
> and the data from bands.x calculation, and found some obvious
> differences , for example , at kpoint (0.00 0.000 0.8803) , output of
> nscf calculation gave data below :
> k = 0.0000 0.0000 0.8803 band energies (ev):
> -23.2631 -22.8169 -22.8148 -21.5536 -21.5517 -19.6376 -19.6331 -19.2573
> -18.8505 -18.8483 -17.7098 -17.7079 -17.3344 -17.3317 -15.8326 -15.7203
> -15.7153 -15.5144 -15.5128 -15.0403 -15.0395 -13.5446 -13.5400 -13.5214
> -13.5210 -12.6873 -12.6836 -11.6226 -11.3921 -11.3913 -11.0763 -11.0745
> -11.0744 -11.0738 -10.9811 -10.9786 -10.0482 -9.7632 -9.7609 -8.5038
> -8.5037 -8.3616 -8.3610 -7.6188 -7.6184 -7.3844 -6.9549 -6.9522
> -6.9467 -6.9088 -6.3798 -6.3782 -5.0396 -5.0385 -4.8055 -4.8016
> -2.9700 -2.3738 -2.3735 -2.1789 -2.1764 -1.8244 -1.8197 -0.1813
> 0.3902 0.3909 0.4404 0.5333 0.6119 0.6178 0.6886 0.7548
> 0.7578 0.7763 1.1057 1.1764 1.2288 1.2302 1.3717 1.4616
> while, bands data from bands.x is
> 0.000000 0.000000 0.880282
> -23.263 -22.817 -22.815 -21.554 -21.552 -19.638 -19.633 -19.257
> -18.850 -18.848
> -17.334 -17.332 -17.710 -15.833 -17.708 -15.514 -15.513 -15.720
> -15.715 -15.040
> -15.040 -13.540 -13.545 -12.687 -12.684 -13.521 -13.521 -11.623
> -11.075 -11.076
> -11.392 -11.391 -11.074 -11.074 -9.763 -9.761 -8.504 -8.504 -10.048 -8.362
> -8.361 -7.618 -7.619 -7.384 -6.955 -6.947 -6.909 -6.952 -6.380 -2.970
> -2.374 -6.378 -4.805 -4.802 -5.040 -5.038 -2.374 -2.179 -2.176 -1.824
> -1.820 -0.181 0.390 0.391 0.440 0.533 0.612 0.618 0.689 0.755
> 0.758 0.776 1.176 1.106 1.229 1.230 * *1.372* -10.979 -10.981* 1.462
>
> How to explain this difference ? My input files are attached.
The difference is in the out-put precision. They are actually same at
the same out-put format.
>
>
>
>
> --
> Hai-Ping Lan
> Department of Electronics ,
> Peking University , Bejing, 100871
> lanhaiping at gmail.com <mailto:lanhaiping at gmail.com>, hplan at pku.edu.cn
> <mailto:hplan at pku.edu.cn>
>
>
>
> --
> Hai-Ping Lan
> Department of Electronics ,
> Peking University , Bejing, 100871
> lanhaiping at gmail.com <mailto:lanhaiping at gmail.com>, hplan at pku.edu.cn
> <mailto:hplan at pku.edu.cn>
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--
Liping YU, PhD Candidate
Department of Physics & Center for High Performance Simulation
North Carolina State University, Raleigh, NC 27695, USA

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