[Pw_forum] Four Electron Pseudopotnetial for tin: US vs NC-PP

[Sven Heiles]

Dear Quantum Espresso users.

Our group is dealing with the global optimizations of clusters using 
Quantum Espresso. In the moment we investigate
the Mn-Sn system for which it is known that a considerable charge 
transfer between Mn(positive) and Sn(negative) occurs. In order to model
the clusters in a finite time it would be useful only to use a PP for 
the four valence electrons of tin while for Mn it is no problem
to use 15 electrons (only one or two Mn are used). The Mn-PP is 
generated using the rrkjus fitting routine but the Sn-PP generation 
always fails if only four electrons
are used for the ultra-soft PP. We tested to generate the 14 electron 
US-PP for tin in analogy to the Pb-US-PP found in the QE PP library and 
were able to generate a PP.
Unfortunately, that many electrons are not of much use in our global 
optimization calculations.
On the other hand the generation of a NC-PP with four electrons for tin 
is able to reproduce bulk and
dimer properties but a similar procedure for Mn is not of much use. Does 
someone has an idea what the problem for the 4 electron
US-PP for tin could be? Please find the generation parameters below.

All the best

Sven

&input
     title='Sn',
     zed=50.0,
     rel=1,
     iswitch=3,
     config='[Kr] 4d10.0 5s2.0 5p2.0 6d-2.0',
     dft='LDA',
  /
  &inputp
     lloc=2,
     pseudotype=3,
     file_pseudopw='Sn.pz-rrkjus.UPF',
     author='',
  /
5
5S  1  0  2.00  0.00  2.50  2.50
5S  1  0  0.00  0.05  2.50  2.50
5P  2  1  2.00  0.00  2.70  2.90
5P  2  1  0.00  0.05  2.70  2.90
6D  3  2 -2.00  0.15  2.70  2.70


-- 
Dipl. Ing. Sven Heiles
Technische Universität Darmstadt
AK Schäfer
Eduard-Zintl-Institut
Petersenstraße 20
D-64287 Darmstadt – Germany

Phone: ++49-(0)6151-164397
Fax: ++49-(0)6151-166024
Web:http://www.tu-darmstadt.de/fb/ch/cluster/schaefer.tud