Simple 3C-SiC ground state

[Fabio Fumi]

I'm new here, so please be patient with my dumb questions!

I've got some experimental expertise about the electronic structure of a-SiC:H and I'd really like to gain experience on this very good DFT toolset, on the same materials, to start with.

Amorphous alloys is far beyond my initial targets, so I though about starting with the simplest structure: 3C-SiC. My first "guess" for an input file is based on the Silicon example, replacing second atom with Carbon and setting a proper lattice constant.

After some initial guessing to find rgkmax (to fix "2*gkmax > gmaxvr" errors), this is my new "guessed" input:

    <title>3C-SiC</title>

    <structure speciespath="../../species/">
        <crystal scale="4.3596">
            <basevect>0.00 0.50 0.50</basevect>
            <basevect>0.50 0.00 0.50</basevect>
            <basevect>0.50 0.50 0.00</basevect>
        </crystal>
        <species speciesfile="C.xml" rmt="0.9">
            <atom coord="0.00 0.00 0.00" />
        </species>
        <species speciesfile="Si.xml" rmt="0.9">
            <atom coord="0.25 0.25 0.25" />
        </species>
    </structure>

    <groundstate ngridk="2 2 2" mixer="lin" rgkmax="4.5"/>

which unfortunately still gives some errors:

Warning(findband): no energy limits found for l= 0
E-bottom   -1000.000000        E-top  -0.7625000000    

Warning(linengy): linearisation energy not found
 for species    2 and atom    1
 APW angular momentum    0
 order    1
 and s.c. loop     1
...

I've tried to understand what to optimize, but couldn't find much help, even looking into source code. 

So, I'm kindly asking some help from you experts!

 thanks
 Fabio (Rome - Italy)


 

[Fabio Fumi]

Hi... no-one who can help here?