[QE-users] Hard PSP for copper

[Vahid Askarpour]

Just an update to my earlier email and hopefully a help to future users. I managed to generate a hard PSP not with the ld1.x code but with the Opium code. Although the PseudoDojo website does have a few hard PSPs, they are not hard enough. For Cu, the authors of PRB94, 155105 (2016) use a cutoff of 240Ry.

Cheers,
Vahid

> On Sep 14, 2020, at 8:56 AM, Vahid Askarpour <vh261281 at dal.ca> wrote:
> 
> Dear QE Community,
> 
> I am attempting to generate a hard PSP for copper (to calculate the electrical conductivity of pure copper) by including the semi-core states as done in the atomic code manual. The semi-core states are essential for a correct evaluation of conductivity.
> 
> The spreads are:
> 
>     s(3S/3S) =  1.000000  <r> =   0.7133  <r2> =    0.5889  r(max) =   0.6112
>     s(3P/3P) =  1.000000  <r> =   0.7502  <r2> =    0.6671  r(max) =   0.6189
>     s(3D/3D) =  1.000000  <r> =   1.0470  <r2> =    1.5711  r(max) =   0.5961
>     s(4S/4S) =  1.000000  <r> =   2.8937  <r2> =    9.8815  r(max) =   2.2428
> 
> 
> My input file is:
> 
> &INPUT
>  title='Cu',
>  zed=29,
>  config='[Ar] 3d10 4s1',
>  rel=1,
>  dft='LDA'
>  iswitch=3,
>  nld=3,
>  rlderiv=2.41,
>  eminld=-10.0,
>  emaxld=4.0,
>  deld=0.01,
> /
> &INPUTP
>  pseudotype=2
>  lloc=0,
> ! rcloc=1.05
>  nlcc=.true.
>  file_pseudopw=‘Cu.UPF',
>  tm=.true.,
> /
> 3
> 3P  2  1  6.00   0.00  1.25  1.25  0.0
> 3D  3  2 10.00  0.00  1.05  1.05  0.0
> 3S  1  0  2.00   0.00  1.10  1.10  0.0
> &TEST
>  file_pseudo=‘Cu.UPF'
>  nconf=1
>  configts(1)='3s2 3p6 3d10 4s1'
>  ecutmin=50
>  ecutmax=500
>  decut=50
> /
> 
> In the output, I get
> 
>     n l     nl             e AE (Ry)        e PS (Ry)    De AE-PS (Ry) 
>     1 0     3S   1( 2.00)       -8.38991       -8.38991       -0.00000
>     2 1     3P   1( 6.00)       -5.29424       -5.29425        0.00000
>     3 2     3D   1(10.00)      -0.39133       -0.39134        0.00000
>     2 0     4S   1( 1.00)       -0.35756       -0.40614        0.04858  !
> 
> The 3S, 3P and 3D match. The last one does not but the manual says it might not. 
> 
> The convergence is reached at
> 
>     Cutoff (Ry) :  200.0
>                           N = 1       N = 2       N = 3
>     E(L=0) =        -8.3893 Ry   -0.4061 Ry    0.0005 Ry
>     E(L=1) =        -5.2513 Ry   -0.0602 Ry    0.0230 Ry
>     E(L=2) =        -0.2263 Ry    0.0347 Ry    0.0793 Ry
> 
> Here 3P and 3D energies are off by 40 and 170mRy. Using P or D as reference with proper lloc does not improve the energy discrepancy.
> 
> And if I use lloc=-1 with rcloc=1.05, I get
> 
>     n l     nl             e AE (Ry)        e PS (Ry)    De AE-PS (Ry) 
>     1 0     3S   1( 2.00)       -8.38991       -8.38991       -0.00000
>     2 1     3P   1( 6.00)       -5.29424       -5.29425        0.00000
>     3 2     3D   1(10.00)      -0.39133       -0.39134        0.00000
>     2 0     4S   1( 1.00)       -0.35756       -0.35996        0.00240
> 
> 4S energies look better. The convergence is reached at
> 
>     Cutoff (Ry) :  200.0
>                           N = 1       N = 2       N = 3
>     E(L=0) =        -8.3893 Ry   -0.3601 Ry    0.0028 Ry
>     E(L=1) =        -5.2512 Ry   -0.0567 Ry    0.0232 Ry
>     E(L=2) =        -0.2244 Ry    0.0347 Ry    0.0793 Ry
> 
> The 3P and 3D energies are still off by 40 and 170mRy. Changing rcloc from 0.7 to 2.0 (which is too large) does not improve the energy differences for these states.
> 
> It seems that regardless of the choice of lloc, the 3P and 3D energies remain different. 
> 
> I have checked the consistency of the derivatives and wave functions but despite the consistency, phonon calculation with convergence of even 10^-22 results in many negative frequencies not just at Gamma but at many other q-points.
> 
> Is there a trick to making the 3P and 3D energies agree beyond what I have already tried?
> 
> Thank you,
> 
> Vahid
> 
> Vahid Askarpour
> Department of physics and atmospheric science
> Dalhousie University
> Halifax, NS
> 
> 
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