[Pw_forum] Fwd: Re: parameteres of quantum dots

[Giuseppe Mattioli]

Dear Pablo
It seems that you are attempting to perform complex calculations without 
going through a proper training and without supervision. There are several 
critical issues in your input file, and this forum is generally not intended for 
training. I can only point out the bad mistakes, but you should take your 
time to learn the hard way...

> I want to simulate the energies spectrum of CdSe Quantum Dots

What is it? Are you talking about optical absorption spectrum? Are you 
aware of the difference between DFT and TD-DFT?

>      ibrav = 0,
> CELL_PARAMETERS {bohr}
> 
>    32.5033024000     0.0000000000     0.0000000000
>    -16.2516512000    28.1486855853     0.0000000000
>      0.0000000000     0.0000000000    39.8082529177

why a monoclinic cell?

>      ecutwfc = 10.0,ecutrho = 80.0,

poorly unconverged plane wave basis set

> ATOMIC_POSITIONS  {bohr}

find attached an image representing your system, as obtained by opening 
your input with xcrysden. There is clearly something wrong, and apart from 
the position of H atoms, too close to the Cd and Se atoms, the structure 
seems to be the right one. A hint: look for the options of  
ATOMIC_POSITIONS in the pw.x manual.

>      occupations='smearing', smearing='marzari-vanderbilt', 
degauss=0.05

Is your system a metal?

>      noncolin = .false.

useless

>     calculation='bands'

why do you need it?


HTH
Giuseppe


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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
   v. Salaria Km 29,300 - C.P. 10                
   I 00015 - Monterotondo Stazione (RM)          
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