Testing USPP vs NC: electron-phonon matrix elements

[Marti]

Dear developers,

I have calculated the electron-phonon matrix element for graphene with both a norm-conserving and an ultrasoft pseudopotential. While the matrix elements are giving acceptable values for the norm-conserving pseudopotential (see Fig. 2 from https://journals.aps.org/prb/abstract/1 ... .93.125432 ), the values for ultrasoft pseudopotential differ from the norm-conserving one, as can be seen in Fig 1.


https://uab-my.sharepoint.com/:i:/g/per ... w?e=YxC0ah
Fig 1: Squared modulus of the electron phonon-matrix elements at k=K for q from gamma to K. USSP results are red, NC are in green.

Do USPPs require any special attention or action?

The used pseudos are:
-NC: http://www.pseudo-dojo.org/pseudos/nc-s ... d/C.upf.gz
-USPP: https://www.quantum-espresso.org/upf_fi ... sl.0.1.UPF

The ecutwfc and ecutrho for both pseudos are converged up to differences of ~1 meV.

Structures were provided similar void, and have been relaxed to have in-plane stresses lower than 0.03kbar and forces smaller than 1.0e-6 Ry/au.

For completeness, I also provide input files for both scf, ph and epw.

Thanks,

Mart



# USPP SCF

Code: Select all

&control  
    calculation  ='scf'
    restart_mode ='from_scratch',
    pseudo_dir   = '.',
    outdir       ='graphene'
    prefix       ='graphene'
    tstress      = .true.
    tprnfor      = .true.
    wf_collect   =.true.
 /
 &system
                       ibrav = 4,
                   celldm(1) = 4.621162409689604,
                   celldm(3) = 8.087578323,
                         nat = 2
                        ntyp = 1,
                     ecutwfc = 70.0
                     ecutrho = 840
                        nbnd = 16, 
                 occupations ='fixed', 

 /
 &electrons
       startingwfc='atomic+random',
       diagonalization='david',
       conv_thr = 1.0e-12,
        mixing_mode = 'local-TF'
 /
ATOMIC_SPECIES
C  12.0107   C.upf 
ATOMIC_POSITIONS {crystal}
   C  0.000000000    0.000000000    0.50000000     
   C  0.333333333    0.666666667    0.50000000     
K_POINTS {automatic}
32 32 1 0 0 0

#USPP PH

Code: Select all

--
&inputph
outdir = './graphene',
prefix = 'graphene',
fildyn = 'graphene.dyn',
fildvscf = 'dvscf',
ldisp = .true.,
nq1 = 16,
nq2 = 16,
nq3 = 1,
tr2_ph = 1.0d-16
/

#USPP EPW1

Code: Select all

--
&inputepw
  prefix      = 'graphene',
  outdir      = './graphene/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .false.

  wannierize  = .true.
  nbndsub     =  5
  nbndskip    =  0
  num_iter    =  2000
  dis_froz_max= 0.0d0
  proj(1)     = 'f=0.0000000000,0.0000000000,0.500000000:sp3'
  proj(2)     = 'f=0.3333333333,0.6666666667,0.500000000:pz'
  wdata(1) = 'dis_num_iter      =  1000'
  wdata(2) = 'guiding_centres = true'
  wdata(3) = 'bands_plot = .true.'
  wdata(4) = 'begin kpoint_path'
  wdata(5) = 'G 0.0000000000     0.0000000000     0.0000000000  M 0.5000000000     0.0000000000     0.0000000000'
  wdata(6) = 'M 0.5000000000     0.0000000000     0.0000000000  K 0.3333333333     0.3333333333     0.0000000000'
  wdata(7) = 'K 0.3333333333     0.3333333333     0.0000000000  G 0.0000000000     0.0000000000     0.0000000000'
  wdata(8) = 'end kpoint_path'
  

  elecselfen  = .false. 
  phonselfen  = .false.
  a2f         = .false.
  

  
  eptemp = 300 !
  ngaussw = 0
  degaussq = 0.03 ! meV
  degaussw = 0.01 ! eV  


  efermi_read = .true.
  fermi_energy = -2.5441
  !fsthick      = 14.000

  nkf1         = 32
  nkf2         = 32
  nkf3         = 1
  nqf1         = 16
  nqf2         = 16
  nqf3         = 1

  nk1         = 32
  nk2         = 32
  nk3         = 1
  nq1         = 16
  nq2         = 16
  nq3         = 1
 /
      30 cartesian
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
   0.000000000000000E+00   0.721687836487043E-01   0.000000000000000E+00
   0.000000000000000E+00   0.144337567297409E+00   0.000000000000000E+00
   0.000000000000000E+00   0.216506350946113E+00   0.000000000000000E+00
   0.000000000000000E+00   0.288675134594817E+00   0.000000000000000E+00
   0.000000000000000E+00   0.360843918243522E+00   0.000000000000000E+00
   0.000000000000000E+00   0.433012701892226E+00   0.000000000000000E+00
   0.000000000000000E+00   0.505181485540930E+00   0.000000000000000E+00
   0.000000000000000E+00  -0.577350269189635E+00   0.000000000000000E+00
   0.625000000000054E-01   0.108253175473056E+00   0.000000000000000E+00
   0.625000000000054E-01   0.180421959121761E+00   0.000000000000000E+00
   0.625000000000054E-01   0.252590742770465E+00   0.000000000000000E+00
   0.625000000000054E-01   0.324759526419169E+00   0.000000000000000E+00
   0.625000000000054E-01   0.396928310067874E+00   0.000000000000000E+00
   0.625000000000054E-01   0.469097093716578E+00   0.000000000000000E+00
   0.625000000000054E-01   0.541265877365282E+00   0.000000000000000E+00
   0.125000000000011E+00   0.216506350946113E+00   0.000000000000000E+00
   0.125000000000011E+00   0.288675134594817E+00   0.000000000000000E+00
   0.125000000000011E+00   0.360843918243522E+00   0.000000000000000E+00
   0.125000000000011E+00   0.433012701892226E+00   0.000000000000000E+00
   0.125000000000011E+00   0.505181485540930E+00   0.000000000000000E+00
   0.125000000000011E+00   0.577350269189635E+00   0.000000000000000E+00
   0.187500000000016E+00   0.324759526419169E+00   0.000000000000000E+00
   0.187500000000016E+00   0.396928310067874E+00   0.000000000000000E+00
   0.187500000000016E+00   0.469097093716578E+00   0.000000000000000E+00
   0.187500000000016E+00   0.541265877365282E+00   0.000000000000000E+00
   0.250000000000021E+00   0.433012701892226E+00   0.000000000000000E+00
   0.250000000000021E+00   0.505181485540930E+00   0.000000000000000E+00
   0.250000000000021E+00   0.577350269189635E+00   0.000000000000000E+00
   0.312500000000027E+00   0.541265877365282E+00   0.000000000000000E+00

#USPP EPW2

Code: Select all

--
&inputepw
  prefix      = 'graphene',
  outdir      = './graphene/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .true.
  epbwrite    = .false.
  epbread     = .false.
  epwwrite    = .false.
  epwread     = .true.
  lpolar      = .false.

  wannierize  = .false.
  nbndsub     =  5
  nbndskip    =  0
  num_iter    =  2000
  dis_froz_max= 0.0d0
  proj(1)     = 'f=0.0000000000,0.0000000000,0.500000000:sp3'
  proj(2)     = 'f=0.3333333333,0.6666666667,0.500000000:pz'
  wdata(1) = 'dis_num_iter      =  1000'
  wdata(2) = 'guiding_centres = true'
  wdata(3) = 'bands_plot = .true.'
  wdata(4) = 'begin kpoint_path'
  wdata(5) = 'G 0.0000000000     0.0000000000     0.0000000000  M 0.5000000000     0.0000000000     0.0000000000'
  wdata(6) = 'M 0.5000000000     0.0000000000     0.0000000000  K 0.3333333333     0.3333333333     0.0000000000'
  wdata(7) = 'K 0.3333333333     0.3333333333     0.0000000000  G 0.0000000000     0.0000000000     0.0000000000'
  wdata(8) = 'end kpoint_path'
  

  elecselfen  = .false. 
  phonselfen  = .false.
  a2f         = .false.
  

  
  eptemp = 300 !
  ngaussw = 0
  degaussq = 0.03 ! meV
  degaussw = 0.01 ! eV  


  prtgkk = .true.
  efermi_read = .true.
  fermi_energy = -2.5441
  fsthick      = 27.000

  filkf = 'Kpoint.dat'
  filqf = 'qpath.dat'

  nk1         = 32
  nk2         = 32
  nk3         = 1
  nq1         = 16
  nq2         = 16
  nq3         = 1
 /
      30 cartesian
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
   0.000000000000000E+00   0.721687836487043E-01   0.000000000000000E+00
   0.000000000000000E+00   0.144337567297409E+00   0.000000000000000E+00
   0.000000000000000E+00   0.216506350946113E+00   0.000000000000000E+00
   0.000000000000000E+00   0.288675134594817E+00   0.000000000000000E+00
   0.000000000000000E+00   0.360843918243522E+00   0.000000000000000E+00
   0.000000000000000E+00   0.433012701892226E+00   0.000000000000000E+00
   0.000000000000000E+00   0.505181485540930E+00   0.000000000000000E+00
   0.000000000000000E+00  -0.577350269189635E+00   0.000000000000000E+00
   0.625000000000054E-01   0.108253175473056E+00   0.000000000000000E+00
   0.625000000000054E-01   0.180421959121761E+00   0.000000000000000E+00
   0.625000000000054E-01   0.252590742770465E+00   0.000000000000000E+00
   0.625000000000054E-01   0.324759526419169E+00   0.000000000000000E+00
   0.625000000000054E-01   0.396928310067874E+00   0.000000000000000E+00
   0.625000000000054E-01   0.469097093716578E+00   0.000000000000000E+00
   0.625000000000054E-01   0.541265877365282E+00   0.000000000000000E+00
   0.125000000000011E+00   0.216506350946113E+00   0.000000000000000E+00
   0.125000000000011E+00   0.288675134594817E+00   0.000000000000000E+00
   0.125000000000011E+00   0.360843918243522E+00   0.000000000000000E+00
   0.125000000000011E+00   0.433012701892226E+00   0.000000000000000E+00
   0.125000000000011E+00   0.505181485540930E+00   0.000000000000000E+00
   0.125000000000011E+00   0.577350269189635E+00   0.000000000000000E+00
   0.187500000000016E+00   0.324759526419169E+00   0.000000000000000E+00
   0.187500000000016E+00   0.396928310067874E+00   0.000000000000000E+00
   0.187500000000016E+00   0.469097093716578E+00   0.000000000000000E+00
   0.187500000000016E+00   0.541265877365282E+00   0.000000000000000E+00
   0.250000000000021E+00   0.433012701892226E+00   0.000000000000000E+00
   0.250000000000021E+00   0.505181485540930E+00   0.000000000000000E+00
   0.250000000000021E+00   0.577350269189635E+00   0.000000000000000E+00
   0.312500000000027E+00   0.541265877365282E+00   0.000000000000000E+00

#NC SCF

Code: Select all

&CONTROL
  calculation='scf',
  outdir='graphene',
  tstress = .true.
  tprnfor = .true.
  prefix='graphene',
  pseudo_dir='./',
  verbosity='low',
  wf_collect=.true.,
/

&SYSTEM
  ibrav=4,
  celldm(1)= 4.629208284320491
  celldm(3)= 8.073660395766156
  nat=2,
  ntyp=1,
  ecutwfc=100,
  input_dft='LDA',
  occupations='fixed'
  nbnd = 16
/
&ELECTRONS
       startingwfc='atomic+random',
       diagonalization='david',
       conv_thr = 1.0e-12,
        mixing_mode = 'local-TF'
/
ATOMIC_SPECIES
  C 12.010700d0 C.upf
K_POINTS {automatic}
 32 32 1 0 0 0
ATOMIC_POSITIONS (crystal)
C        0.000000000   0.000000000   0.50000000000000
C        0.333333333   0.666666667   0.50000000000000

#NC PH

Code: Select all

--
&inputph
outdir = './graphene',
prefix = 'graphene',
fildyn = 'graphene.dyn',
fildvscf = 'dvscf',
ldisp = .true.,
nq1 = 16,
nq2 = 16,
nq3 = 1,
tr2_ph = 1.0d-16
/

#NC EPW1

Code: Select all

--
&inputepw
  prefix      = 'graphene',
  outdir      = './graphene/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .false.

  wannierize  = .true.
  nbndsub     =  5
  nbndskip    =  0
  num_iter    =  2000
  dis_froz_max= 0.0d0
  proj(1)     = 'f=0.0000000000,0.0000000000,0.500000000:sp3'
  proj(2)     = 'f=0.3333333333,0.6666666667,0.500000000:pz'
  wdata(1) = 'dis_num_iter      =  1000'
  wdata(2) = 'guiding_centres = true'
  wdata(3) = 'bands_plot = .true.'
  wdata(4) = 'begin kpoint_path'
  wdata(5) = 'G 0.0000000000     0.0000000000     0.0000000000  M 0.5000000000     0.0000000000     0.0000000000'
  wdata(6) = 'M 0.5000000000     0.0000000000     0.0000000000  K 0.3333333333     0.3333333333     0.0000000000'
  wdata(7) = 'K 0.3333333333     0.3333333333     0.0000000000  G 0.0000000000     0.0000000000     0.0000000000'
  wdata(8) = 'end kpoint_path'
  

  elecselfen  = .false. 
  phonselfen  = .false.
  a2f         = .false.
  

  
  eptemp = 300 !
  ngaussw = 0
  degaussq = 0.03 ! meV
  degaussw = 0.01 ! eV  


  efermi_read = .true.
  fermi_energy = -2.5596
  !fsthick      = 14.000

  nkf1         = 32
  nkf2         = 32
  nkf3         = 1
  nqf1         = 16
  nqf2         = 16
  nqf3         = 1

  nk1         = 32
  nk2         = 32
  nk3         = 1
  nq1         = 16
  nq2         = 16
  nq3         = 1
 /
      30 cartesian
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
   0.000000000000000E+00   0.721687836486904E-01   0.000000000000000E+00
   0.000000000000000E+00   0.144337567297381E+00   0.000000000000000E+00
   0.000000000000000E+00   0.216506350946071E+00   0.000000000000000E+00
   0.000000000000000E+00   0.288675134594762E+00   0.000000000000000E+00
   0.000000000000000E+00   0.360843918243452E+00   0.000000000000000E+00
   0.000000000000000E+00   0.433012701892143E+00   0.000000000000000E+00
   0.000000000000000E+00   0.505181485540833E+00   0.000000000000000E+00
   0.000000000000000E+00  -0.577350269189523E+00   0.000000000000000E+00
   0.624999999999934E-01   0.108253175473036E+00   0.000000000000000E+00
   0.624999999999934E-01   0.180421959121726E+00   0.000000000000000E+00
   0.624999999999934E-01   0.252590742770416E+00   0.000000000000000E+00
   0.624999999999934E-01   0.324759526419107E+00   0.000000000000000E+00
   0.624999999999934E-01   0.396928310067797E+00   0.000000000000000E+00
   0.624999999999934E-01   0.469097093716488E+00   0.000000000000000E+00
   0.624999999999934E-01   0.541265877365178E+00   0.000000000000000E+00
   0.124999999999987E+00   0.216506350946071E+00   0.000000000000000E+00
   0.124999999999987E+00   0.288675134594762E+00   0.000000000000000E+00
   0.124999999999987E+00   0.360843918243452E+00   0.000000000000000E+00
   0.124999999999987E+00   0.433012701892143E+00   0.000000000000000E+00
   0.124999999999987E+00   0.505181485540833E+00   0.000000000000000E+00
   0.124999999999987E+00   0.577350269189523E+00   0.000000000000000E+00
   0.187499999999980E+00   0.324759526419107E+00   0.000000000000000E+00
   0.187499999999980E+00   0.396928310067797E+00   0.000000000000000E+00
   0.187499999999980E+00   0.469097093716488E+00   0.000000000000000E+00
   0.187499999999980E+00   0.541265877365178E+00   0.000000000000000E+00
   0.249999999999973E+00   0.433012701892143E+00   0.000000000000000E+00
   0.249999999999973E+00   0.505181485540833E+00   0.000000000000000E+00
   0.249999999999973E+00   0.577350269189523E+00   0.000000000000000E+00
   0.312499999999967E+00   0.541265877365178E+00   0.000000000000000E+00

#NC EPW2

Code: Select all

--
&inputepw
  prefix      = 'graphene',
  outdir      = './graphene/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .true.
  epbwrite    = .false.
  epbread     = .false.
  epwwrite    = .false.
  epwread     = .true.
  lpolar      = .false.

  wannierize  = .false.
  nbndsub     =  5
  nbndskip    =  0
  num_iter    =  2000
  dis_froz_max= 0.0d0
  proj(1)     = 'f=0.0000000000,0.0000000000,0.500000000:sp3'
  proj(2)     = 'f=0.3333333333,0.6666666667,0.500000000:pz'
  wdata(1) = 'dis_num_iter      =  1000'
  wdata(2) = 'guiding_centres = true'
  wdata(3) = 'bands_plot = .true.'
  wdata(4) = 'begin kpoint_path'
  wdata(5) = 'G 0.0000000000     0.0000000000     0.0000000000  M 0.5000000000     0.0000000000     0.0000000000'
  wdata(6) = 'M 0.5000000000     0.0000000000     0.0000000000  K 0.3333333333     0.3333333333     0.0000000000'
  wdata(7) = 'K 0.3333333333     0.3333333333     0.0000000000  G 0.0000000000     0.0000000000     0.0000000000'
  wdata(8) = 'end kpoint_path'
  

  elecselfen  = .false. 
  phonselfen  = .false.
  a2f         = .false.
  

  
  eptemp = 300 !
  ngaussw = 0
  degaussq = 0.03 ! meV
  degaussw = 0.01 ! eV  


  prtgkk = .true.
  efermi_read = .true.
  fermi_energy = -2.5596
  fsthick      = 27.000

  filkf = 'Kpoint.dat'
  filqf = 'qpath.dat'

  nk1         = 32
  nk2         = 32
  nk3         = 1
  nq1         = 16
  nq2         = 16
  nq3         = 1
 /
      30 cartesian
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
   0.000000000000000E+00   0.721687836486904E-01   0.000000000000000E+00
   0.000000000000000E+00   0.144337567297381E+00   0.000000000000000E+00
   0.000000000000000E+00   0.216506350946071E+00   0.000000000000000E+00
   0.000000000000000E+00   0.288675134594762E+00   0.000000000000000E+00
   0.000000000000000E+00   0.360843918243452E+00   0.000000000000000E+00
   0.000000000000000E+00   0.433012701892143E+00   0.000000000000000E+00
   0.000000000000000E+00   0.505181485540833E+00   0.000000000000000E+00
   0.000000000000000E+00  -0.577350269189523E+00   0.000000000000000E+00
   0.624999999999934E-01   0.108253175473036E+00   0.000000000000000E+00
   0.624999999999934E-01   0.180421959121726E+00   0.000000000000000E+00
   0.624999999999934E-01   0.252590742770416E+00   0.000000000000000E+00
   0.624999999999934E-01   0.324759526419107E+00   0.000000000000000E+00
   0.624999999999934E-01   0.396928310067797E+00   0.000000000000000E+00
   0.624999999999934E-01   0.469097093716488E+00   0.000000000000000E+00
   0.624999999999934E-01   0.541265877365178E+00   0.000000000000000E+00
   0.124999999999987E+00   0.216506350946071E+00   0.000000000000000E+00
   0.124999999999987E+00   0.288675134594762E+00   0.000000000000000E+00
   0.124999999999987E+00   0.360843918243452E+00   0.000000000000000E+00
   0.124999999999987E+00   0.433012701892143E+00   0.000000000000000E+00
   0.124999999999987E+00   0.505181485540833E+00   0.000000000000000E+00
   0.124999999999987E+00   0.577350269189523E+00   0.000000000000000E+00
   0.187499999999980E+00   0.324759526419107E+00   0.000000000000000E+00
   0.187499999999980E+00   0.396928310067797E+00   0.000000000000000E+00
   0.187499999999980E+00   0.469097093716488E+00   0.000000000000000E+00
   0.187499999999980E+00   0.541265877365178E+00   0.000000000000000E+00
   0.249999999999973E+00   0.433012701892143E+00   0.000000000000000E+00
   0.249999999999973E+00   0.505181485540833E+00   0.000000000000000E+00
   0.249999999999973E+00   0.577350269189523E+00   0.000000000000000E+00
   0.312499999999967E+00   0.541265877365178E+00   0.000000000000000E+00

[roxana]

Hi Marti,

Could you also provide plots of the wannierized band structures and interpolated phonon dispersions?

For debugging purposes, it would be useful if some coarser k- and q-meshes were found where the problem exists. From your plot, it appears that the issue is for one of the acoustic branches.

In principle, you can output the e-ph matrix elements in q-e as well is you replace the following 4 files in PHONON/PH and use electron_phonon='simple' flag in ph.in. The files can be found at:

https://drive.google.com/drive/folders/ ... sp=sharing

Best,
Roxana

[Marti]

Dear Roxana,

Thank you for your response and the QE modification for plotting the electron-phonon matrix element, and I apologize for the delay answering.

As you suggested Ive obtained the electron and phonon band structure for graphene. However while doing it Ive realized that ZA phonons near ? were not accurate for US pseudopotential. Therefore, I couldnt properly determine if the weird electron-phonon matrix element was caused by changing from NC to USPP or the bad phonons near ?.

Graphene EPW electron band structure for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... A?e=fg3YmL

Graphene EPW phonon dispersion for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... g?e=I3n126

Since I failed to obtain a good phonon structure with available USPP (from QE pseudopotential database) for graphene, I moved to SiC (here I provide EPW bands and electron-phonon matrix elements) and Si (for which, I provide EPW bands and electron-phonon matrix elements together with first-principles ones).

For SiC, I have plotted both electron and phonon band structure, with a good agreement between NC and US pseudopotentials. However, the obtained electron-phonon matrix elements present a similar discrepancy near ? similar to the one in graphene.

SiC EPW electron bandstructure for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... g?e=wrAa9t

SiC EPW phonon dispersion for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... Q?e=eJMiEP

SiC electron-phonon EPW matrix elements for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... Q?e=zL8AvI

Finally, for Si I have also obtained good agreement in bands between NC and US, but when plotting the electron-phonon matrix elements I have also got those weird deformations near ?. As you proposed I plotted the first-principles results, focusing on the weird one. I have obtained a quite good agreement for the NC pseudo. On the other hand, for USPP I obtain a first-principles result that, despite being in agreement with the NC result (so no weird deformation near ?), does not coincide with the EPW result.

Si EPW electron bandstructure for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... Q?e=uqHBfu

Si EPW phonon dispersion for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... w?e=9XmY3q

Si electron-phonon EPW matrix elements for NC and US:
https://uab-my.sharepoint.com/:i:/g/per ... g?e=8IVhab

Si electron-phonon FC results for NC and US for 3rd phonon branch near ?:
https://uab-my.sharepoint.com/:i:/g/per ... w?e=6K2sj9

Si electron phonon matrix elements comparing EPW and QE results for US:
https://uab-my.sharepoint.com/:i:/g/per ... g?e=gXKi4X

Si electron phonon matrix elements comparing EPW and QE results for NC:
https://uab-my.sharepoint.com/:i:/g/per ... A?e=i7fV9m

Therefore the weird deformation near ? is a common thing in my results for USPP, and they are not present at least in the Si case in first-principles calculations.

For completeness, I also provide the scf and EPW inputs.

SCF Si NC:

Code: Select all

 &control
    calculation     = 'scf'
    prefix          = 'si'
    restart_mode    = 'from_scratch'
    wf_collect      = .true.
    pseudo_dir      = './'
    outdir          = './si'
    tprnfor         = .true.
    tstress         = .true.
    forc_conv_thr = 5.0d-5
    nstep        = 60
 /
 &system
    ibrav           = 2
    celldm(1)       = 10.19342175021866
    nat             = 2
    ntyp            = 1
    ecutwfc         = 100.0
    nbnd            = 4 
 /
 &electrons
    diagonalization = 'david'
    mixing_beta     = 0.3
    conv_thr        = 1.0d-12
/
ATOMIC_SPECIES
  Si  28.0855     Si.upf
ATOMIC_POSITIONS alat
  Si  0.00  0.00  0.00
  Si   0.25  0.25  0.25
K_POINTS automatic
15 15 15 0 0 0

EPW Si NC:

Code: Select all

--
&inputepw
  prefix      = 'si'
  outdir      = './si/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .false.

  wannierize  = .true.
  nbndsub     =  4
  nbndskip    =  0
  num_iter    = 2000
  proj(1)     = 'f=0.0000000000,0.0000000000,0.000000000:sp3'
  wdata(1) = 'guiding_centres = true'


  efermi_read = .true.
  fermi_energy= 6.2464
  elecselfen  = .false.
  phonselfen  = .false.
  a2f         = .false.
  prtgkk      = .true.
  fsthick     = 30.0 

  
  filqf       = 'path.dat'
  nkf1        = 1
  nkf2        = 1
  nkf3        = 1

  nk1         = 15
  nk2         = 15
  nk3         = 15
  nq1         = 5
  nq2         = 5
  nq3         = 5
 /
   10 {cartesian}
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
  -0.200000000000026E+00   0.200000000000026E+00  -0.200000000000026E+00
  -0.400000000000053E+00   0.400000000000053E+00  -0.400000000000053E+00
   0.000000000000000E+00   0.400000000000053E+00   0.000000000000000E+00
  -0.200000000000026E+00   0.600000000000079E+00  -0.200000000000026E+00
   0.600000000000079E+00  -0.200000000000026E+00   0.600000000000079E+00
   0.400000000000053E+00   0.555111512312578E-16   0.400000000000053E+00
   0.000000000000000E+00   0.800000000000105E+00   0.000000000000000E+00
   0.800000000000105E+00   0.000000000000000E+00   0.800000000000105E+00
   0.600000000000079E+00  -0.200000000000026E+00   0.100000000000013E+01

SCF Si US:

Code: Select all

 &control
    calculation     = 'scf'
    prefix          = 'si'
    restart_mode    = 'from_scratch'
    wf_collect      = .true.
    pseudo_dir      = './'
    outdir          = './si'
    tprnfor         = .true.
    tstress         = .true.
    forc_conv_thr = 5.0d-5
    nstep        = 60
 /
 &system
    ibrav           = 2
    celldm(1)       = 10.202280157854611
    nat             = 2
    ntyp            = 1
    ecutwfc         = 60.0
    ecutrho         = 720
    nbnd            = 4
 /
 &electrons
    diagonalization = 'david'
    mixing_beta     = 0.3
    conv_thr        = 1.0d-12
/
ATOMIC_SPECIES
  Si  28.0855     Si.upf
ATOMIC_POSITIONS alat
  Si  0.00  0.00  0.00
  Si   0.25  0.25  0.25
K_POINTS automatic
15 15 15 0 0 0

EPW Si US:

Code: Select all

--
&inputepw
  prefix      = 'si'
  outdir      = './si/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .false.

  wannierize  = .true.
  nbndsub     =  4
  nbndskip    =  0
  num_iter    = 2000
  !dis_win_max       =  16.5
  dis_froz_max      =  6.43685
  proj(1)     = 'f=0.0000000000,0.0000000000,0.000000000:sp3'
  wdata(1) = 'dis_num_iter      =  2000'
  wdata(2) = 'guiding_centres = true'


  efermi_read = .true.
  fermi_energy=  6.43685
  elecselfen  = .false.
  phonselfen  = .false.
  a2f         = .false.
  prtgkk      = .true.
  fsthick     = 30.0 

  
  filqf       = 'path.dat'
  nkf1        = 1
  nkf2        = 1
  nkf3        = 1

  nk1         = 15
  nk2         = 15
  nk3         = 15
  nq1         = 5
  nq2         = 5
  nq3         = 5
 /
   10 {cartesian}
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
  -0.199999999999910E+00   0.199999999999910E+00  -0.199999999999910E+00
  -0.399999999999819E+00   0.399999999999819E+00  -0.399999999999819E+00
   0.000000000000000E+00   0.399999999999819E+00   0.000000000000000E+00
  -0.199999999999910E+00   0.599999999999729E+00  -0.199999999999910E+00
   0.599999999999729E+00  -0.199999999999910E+00   0.599999999999729E+00
   0.399999999999819E+00   0.555111512312578E-16   0.399999999999819E+00
   0.000000000000000E+00   0.799999999999638E+00   0.000000000000000E+00
   0.799999999999638E+00   0.000000000000000E+00   0.799999999999638E+00
   0.599999999999729E+00  -0.199999999999910E+00   0.999999999999548E+00

SCF SiC NC:

Code: Select all

&control
    calculation     = 'scf'
    prefix          = 'sic'
    restart_mode    = 'from_scratch'
    wf_collect      = .true.
    pseudo_dir      = './'
    outdir          = './sic'
    tprnfor         = .true.
    tstress         = .true.
    forc_conv_thr = 5.0d-5
    nstep        = 60
 /
 &system
    ibrav           = 2
    celldm(1)       = 8.276808525081007
    nat             = 2
    ntyp            = 2
    ecutwfc         = 100.0
    nbnd            = 4
 /
 &electrons
    diagonalization = 'david'
    mixing_beta     = 0.3
    conv_thr        = 1.0d-12
/
ATOMIC_SPECIES
  Si  28.0855     Si.upf
  C  12.0107   C.upf
ATOMIC_POSITIONS alat
  Si  0.00  0.00  0.00
  C   0.25  0.25  0.25
K_POINTS automatic
18 18 18 0 0 0

EPW SiC NC:

Code: Select all

--
&inputepw
  prefix      = 'sic'
  amass(1)    = 28.0855
  amass(2)    = 12.0107
  outdir      = './sic/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .true.

  wannierize  = .true.
  nbndsub     =  4
  nbndskip    =  0
  num_iter    = 300
  proj(1)     = 'Si:sp3'   

  elecselfen  = .false.
  phonselfen  = .false.
  a2f         = .false.
  prtgkk      = .true.

  fsthick     = 25.0 
  eptemp      = 20 
  degaussw    = 0.05
  
  filqf       = 'path.dat'
  nkf1        = 1
  nkf2        = 1
  nkf3        = 1

  nk1         = 18
  nk2         = 18
  nk3         = 18
  nq1         = 6
  nq2         = 6
  nq3         = 6
 /
   16 {cartesian}
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
  -0.166666666666666E+00   0.166666666666666E+00  -0.166666666666666E+00
  -0.333333333333333E+00   0.333333333333333E+00  -0.333333333333333E+00
   0.499999999999999E+00  -0.499999999999999E+00   0.499999999999999E+00
   0.000000000000000E+00   0.333333333333333E+00   0.000000000000000E+00
  -0.166666666666666E+00   0.499999999999999E+00  -0.166666666666666E+00
   0.666666666666666E+00  -0.333333333333333E+00   0.666666666666666E+00
   0.499999999999999E+00  -0.166666666666667E+00   0.499999999999999E+00
   0.333333333333333E+00   0.277555756156289E-16   0.333333333333333E+00
   0.000000000000000E+00   0.666666666666666E+00   0.000000000000000E+00
   0.833333333333332E+00  -0.166666666666667E+00   0.833333333333332E+00
   0.666666666666666E+00  -0.555111512312578E-16   0.666666666666666E+00
   0.000000000000000E+00  -0.999999999999999E+00   0.000000000000000E+00
   0.666666666666666E+00  -0.333333333333333E+00   0.999999999999999E+00
   0.499999999999999E+00  -0.166666666666667E+00   0.833333333333332E+00
  -0.333333333333333E+00  -0.999999999999999E+00   0.000000000000000E+00

SCF SiC US:

Code: Select all

 &control
    calculation     = 'scf'
    prefix          = 'sic'
    restart_mode    = 'from_scratch'
    wf_collect      = .true.
    pseudo_dir      = './'
    outdir          = './sic'
    tprnfor         = .true.
    tstress         = .true.
    forc_conv_thr = 5.0d-6
    nstep        = 60
 /
 &system
    ibrav           = 2
    celldm(1)       = 8.273064350019162
    nat             = 2
    ntyp            = 2
    ecutwfc         = 100.0
    ecutrho         = 1200.0
    nbnd            = 4
 /
 &electrons
    diagonalization = 'david'
    mixing_beta     = 0.3
    conv_thr        = 1.0d-12
/
ATOMIC_SPECIES
  Si  28.0855     Si.upf
  C  12.0107   C.upf
ATOMIC_POSITIONS alat
  Si  0.00  0.00  0.00
  C   0.25  0.25  0.25
K_POINTS automatic
18 18 18 0 0 0

EPW SiC US:

Code: Select all

--
&inputepw
  prefix      = 'sic'
  amass(1)    = 28.0855
  amass(2)    = 12.0107
  outdir      = './sic/'
  dvscf_dir   = './save'

  elph        = .true.
  kmaps       = .false.
  epbwrite    = .true.
  epbread     = .false.
  epwwrite    = .true.
  epwread     = .false.
  lpolar      = .true.

  wannierize  = .true.
  nbndsub     =  4
  nbndskip    =  0
  num_iter    = 300
  proj(1)     = 'Si:sp3'   

  elecselfen  = .false.
  phonselfen  = .false.
  a2f         = .false.
  prtgkk      = .true.

  fsthick     = 25.0 
  eptemp      = 20 
  degaussw    = 0.05
  
  filqf       = 'path.dat'
  nkf1        = 1
  nkf2        = 1
  nkf3        = 1

  nk1         = 18
  nk2         = 18
  nk3         = 18
  nq1         = 6
  nq2         = 6
  nq3         = 6
 /
   16 {cartesian}
   0.000000000000000E+00   0.000000000000000E+00   0.000000000000000E+00
  -0.166666666666663E+00   0.166666666666663E+00  -0.166666666666663E+00
  -0.333333333333327E+00   0.333333333333327E+00  -0.333333333333327E+00
   0.499999999999990E+00  -0.499999999999990E+00   0.499999999999990E+00
   0.000000000000000E+00   0.333333333333327E+00   0.000000000000000E+00
  -0.166666666666663E+00   0.499999999999990E+00  -0.166666666666663E+00
   0.666666666666654E+00  -0.333333333333327E+00   0.666666666666654E+00
   0.499999999999990E+00  -0.166666666666663E+00   0.499999999999990E+00
   0.333333333333327E+00   0.277555756156289E-16   0.333333333333327E+00
   0.000000000000000E+00   0.666666666666654E+00   0.000000000000000E+00
   0.833333333333317E+00  -0.166666666666663E+00   0.833333333333317E+00
   0.666666666666654E+00  -0.555111512312578E-16   0.666666666666654E+00
   0.000000000000000E+00  -0.999999999999980E+00   0.000000000000000E+00
   0.666666666666654E+00  -0.333333333333327E+00   0.999999999999980E+00
   0.499999999999990E+00  -0.166666666666663E+00   0.833333333333317E+00
  -0.333333333333327E+00  -0.999999999999980E+00   0.555111512312578E-16

Mart

[roxana]

Hi Marti,

Can you repeat the epw calculations for Si with the use_ws = .true. flag?

Could you please provide your nscf.in, ph.in, and path.dat files as well as US and NC pseudo files for Si and I will try to look over this issue in the coming weeks.

Best,
Roxana

[Marti]

Hi Roxana,

Thank you for your fast response,

As you suggested I repeated the calculations with the use_ws flag. However, it does not significantly modify the results between NC and US pseudopotentials (the deformation near ? is still present).

*The EPW electron-phonon matrix elements for US and NC pseudos, using the use_ws flag
https://uab-my.sharepoint.com/:i:/g/per ... w?e=zIzIPl

You can find the input files, pseudopotentials and path file in the following link:
https://uab-my.sharepoint.com/:u:/g/per ... g?e=zqclXl

Mart

[roxana]

Hi Marti,

Thanks for running more tests and providing the input files. Hopefully, I will get a chance to look over this issue in the coming weeks (this period is quite busy for me).

Best,
Roxana

[roxana]

Hi Marti,

I started running some tests for Si with NC and USPP and I have a couple of questions regarding your results:

1) Does the label "fp" in your plots means frozen phonon?

2) Can you provide the input files for the e-ph matrix elements obtained with QE? Did you used the modified files that I provided to calculate the e-ph matrix elements with QE or a different approach?

Best,
Roxana

[Marti]

Hi Roxana,

The "fp" from my graphs means first principles (directly obtained from QE).

For obtaining them i have used the modified files that you have provided.

*QE INPUT FILE:

Code: Select all

--
&inputph
outdir = './si',
prefix = 'si',
fildyn = 'si.dyn',
fildvscf = 'dvscf',
tr2_ph = 1.0d-16
electron_phonon='simple'
/
Q1 Q2 Q3

*The qpoint list that I have used:

Code: Select all

-0.3500000   0.3500000   0.3500000
-0.3333333   0.3333333   0.3333333
-0.3166667   0.3166667   0.3166667
-0.3000000   0.3000000   0.3000000
-0.2833333   0.2833333   0.2833333
-0.2666667   0.2666667   0.2666667
-0.2500000   0.2500000   0.2500000
-0.2333333   0.2333333   0.2333333
-0.2166667   0.2166667   0.2166667
-0.2000000   0.2000000   0.2000000
-0.1833333   0.1833333   0.1833333
-0.1666667   0.1666667   0.1666667
-0.1500000   0.1500000   0.1500000
-0.1333333   0.1333333   0.1333333
-0.1166667   0.1166667   0.1166667
-0.1000000   0.1000000   0.1000000
-0.0833333   0.0833333   0.0833333
-0.0666667   0.0666667   0.0666667
-0.0500000   0.0500000   0.0500000
-0.0333333   0.0333333   0.0333333
-0.0166667   0.0166667   0.0166667
 0.0000000   0.0000000   0.0000000

And the bash script to generate inputs from those two files:

Code: Select all

#Use: script file_with_qpts
i=1
while read q1 q2 q3 remainder
do
 echo "$i $q1 $q2 $q3"
 sed -e "s:Q1:$q1:g" -e "s:Q2:$q2:g" -e "s:Q3:$q3:g" si.ph.in > si.ph-$i.in
 let "i++"
done < $1

Best,

Mart

[roxana]

Hi Marti,

I updated the USPP implementation in EPW and the corrections were made available in the QE developer branch on gitlab. I hope this would solve the problems you encountered.

Best,
Roxana