[Pw_forum] Errors in PS-PK equation

[Lorenzo Paulatto]

Dear 黄志硕,

First of all, you can find norm-conserving PBE pseudopotentials for 
alkaline metals in the SG15-ONCV library 
<http://www.quantum-simulation.org/potentials/sg15_oncv/>

There are a couple of problems with your input:

1. when defining a pseudo state, the value of N and L that you specify 
refer to the PSEUDO state, not the reference all-electron state. For 
example, the pseudo-4S state has no node, hence it has L=0, N=1 (i.e. it 
is a 1S-like state).


If you fix this, your pseudo will compile, but I think you should keep 
reading.

2.it is practically impossible to do a good pseudopotential with only a 
partial shell, in your case you introduce the 4P orbital, but leave the 
4S out. This is likely to not work well in practice

3. in order to put the 4S orbital, you have to set pseudotype=2, which 
means normconserving with multiple projectors per angular momentum

4. I find that semi-core pseudos work better if you keep the natural 
progression for the number of node, hence in your case:
4S -> zero nodes
5S -> one node
4P -> zero nodes
4D -> zero nodes

In order to have one node in 5S, you need to cut inside its outermost 
node, which accidentally was already done in your case keeping a cutoff 
radius of 1.5 for all states


5. don't forget to check the logarithmic derivative for positive 
energies, to check that the pseudo and all-electron derivatives stay 
close enough (I'm not sure this is true in the input I've put below, you 
may have to add more projectors, i.e.e for 5P)

6. don't forget to plot the pseudo wavefunctions and compare them to the 
all-electron ones, be sure that the pseudized part goes directly and 
smoothly to zero, with no wiggles or other strange features.

7. always test in real solid state systems

  &input
         iswitch=3,

         title='Rb',
         prefix="Rb_ld1"

         rlderiv=2.6,
         eminld=-8.0,
         emaxld=8.0,
         deld=0.01d0,
         nld=4,

         rel=1,
         zed=37.0,
         config="[Ar] 3d10 4s2 4p6 5s0 4d0"
         dft='PBE',
  /
  &inputp
    tm=.true.
    lloc=-1,
    nlcc=.true.
    rcloc=1.5
    rcore=1.2,
    pseudotype=2,
    file_pseudopw='Rb.pbe-mt_scalar.UPF',

    file_screen='Rb_ld1.scr'
    file_beta  ='Rb_ld1.beta'
    !file_wfcusgen   ='Rb_ld1.usc'
    file_wfcusgen   ='Rb_ld1.ncc'
    file_wfcaegen   ='Rb_ld1.aec'
    file_core = 'Rb_core'
    file_screen='Rb_screen'


  /
4
5S  2  0  0.00  0.00  1.50  1.50
4S  1  0  2.00  0.00  1.50  1.50
4P  2  1  6.00  0.00  1.50  1.50
4D  3  2  0.00  0.00  1.50  1.50


On 23/08/17 16:12, 黄志硕 wrote:
>   &input
>          iswitch=3,
> 
>          rlderiv=1.5,
>          eminld=-8.0,
>          emaxld=0.0,
>          deld=0.01d0,
>          nld=4,
> 
>          rel=1,
>          zed=37.0,
>          config="[Ar] 3d10 4s2 4p6 5s0 4d0"
>          dft='PBE',
>   /
>   &inputp
>     tm=.true.
>     lloc=-1,
>     nlcc=.true.
>     rcloc=1.5
>     rcore=1.2,
>     pseudotype=1,
>     file_pseudopw='Rb.pbe-mt_scalar.UPF',
>   /
> 3
> 5S  5  0  0.00  0.00  1.50  1.50
> 4P  4  1  6.00  0.00  1.50  1.50
> 4D  4  2  0.00  0.00  1.50  1.50

-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 442 79822 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/423 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05