​​DECAY COMPARISON
​​Expected behavior  (From EPW : A program for calculating the electron–phonon coupling using maximally localized Wannier functions.  doi:10.1016/j.cpc.2010.08.027.)
​​
 
User-uploaded image: Screenshot+from+2019-04-15+10-35-20.png
​​FIG 1
​​Spatial decay of the largest components of the Hamiltonian H R el e , 0 (a), the dynamical matrix D R p , 0 (b), and the electron–phonon matrix elements g ( 0 , R p ) (c) and
​​g ( R e , 0 ) (d) for fcc Pb. The data are plotted as a function of distance and are taken along several directions.
​​

​​k = 16 16 2, q = 16 16 2

​​
 
User-uploaded image: decay_16162.png
​​
​​

​​k = 21 21 1, q = 7 7 1

​​
 
User-uploaded image: decay_epw_51.png
​​

​​EPW input files

​​Input files reported for the case k = 21 21 1, q = 7 7 1. The case k = 16 16 2, q = 16 16 2 has is identical but for the  k and q grid
​​
​​mpirun -np 21 pw.x -npool 21 < scf.in > scf.out
​​&control
​​     calculation='scf'                    
​​     title ='MoS2'
​​     restart_mode='from_scratch'
​​     pseudo_dir='/home/safiore/SSSP_accuracy_pseudos'
​​     outdir='./'
​​     prefix='MoS2',
​​     !wf_collect=.true.
​​     !verbosity = 'high'
​​  /
​​  &system
​​     ibrav=0
​​     nat=3, 
​​     ntyp=2, 
​​     ecutwfc = 35, 
​​     ecutrho = 240,
​​     !occupations='fixed',
​​     !assume_isolated='2D',
​​
​​  /
​​  &electrons
​​     conv_thr = 1.0d-10                 
​​                
​​  /
​​ ATOMIC_SPECIES
​​  Mo  95.94    Mo_ONCV_PBE-1.0.upf
​​  S   32.065   s_pbe_v1.4.uspp.F.UPF
​​
​​ATOMIC_POSITIONS angstrom
​​Mo          -0.0000000000       1.8386990572      11.5773510440 
​​S            1.5923600935       0.9193495287      10.0139409592 
​​S            1.5923600935       0.9193495287      13.1407611289
​​
​​K_POINTS automatic
​​16 16 1 0 0 0
​​
​​CELL_PARAMETERS angstrom