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Hi! I'd like to use quantum espresso in research of properties of
MoS2 nanoparticles, modified with Co and Ni. This basically means
calculations with 20 to 60 atoms of modified MoS2 slab and 10 to 30
atoms of interacting molecule, as well as 1- and 3-dimensional
periodic calculations with same number of atoms. The atomic species
of interest are: Mo, S, Co, Ni, H, C, N, O, K, Na, Li.<br>
<br>
Before performing real calculations I'd like to reproduce geometry
of several basic with reasonable agreement with expreimental data.
The problem is choise of PP/functional pair. For some time I was
stick with b3lyp and pbe functionals of gaussian-03 package with
full-electron non-periodic calculations, wich resulted in good
agreement with experimental data. However, I cannot find PPs for
this functionals for QE and full-electron approach is a little too
much for my new systems. With quick research I was able to generate
simple PP for H atom, but got 0.78 A H-H bond length instead of
0.74, and runned into incompatibility of ultrasoft PP and Gamma
algorithm. So, I decided to stop and search for advise.<br>
<br>
The questions are:<br>
<ol>
<li>Can someone point a good review about PP approximation (both
math and use)?</li>
<li>As well as planewave approach for basis sets (It is completly
new for me, I used only GTO basis sets before) ?<br>
</li>
<li>And possibly a good library of PP (espetially interested in
desription of generation procedure) ?</li>
<li>What the hell are K-points, given in K_points sections and how
should I choose them for ultrasoft PP ?</li>
<li>Are geometry and energy errors in QE/DFT systematic, i.e. can
I use some corrections coefficient or I should work with them as
random values?</li>
</ol>
<p>Of course, I'm going at least to try to find and read reference
articles for QE, yet my math skills are not very hight.<br>
</p>
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