# Zincblende AlAs - strain perturbation calculation with GGA
# Includes core charges

ndtset 2

#DATASET 1 : Self-consistent GS run

  kptopt1   1
  tolvrs1   1.0d-12

#DATASET 2 : RF run

  getwfk2   -1
  kptopt2   2
    nqpt2   1
     qpt2   0 0 0
   rfdir2   1 0 0
  rfstrs2   3
  tolvrs2   1.0d-8

#Common data

    acell  3*10.68
   diemac  6.0
     ecut  8.0
      ixc  11    #PBE GGA
    natom  2
    nband  4
   nbdbuf  0
    ngkpt  2 2 2
  nshiftk  4
    nstep  100
   ntypat  2
   occopt  1

    rprim  0.0 0.5 0.5
           0.5 0.0 0.5
           0.5 0.5 0.0

   shiftk  0.5 0.5 0.5
           0.5 0.0 0.0
           0.0 0.5 0.0
           0.0 0.0 0.5

    typat  1 2
     xred  0.0  0.0  0.0
           0.25 0.25 0.25
    znucl  13 33

 pp_dirpath "$ABI_PSPDIR"
 pseudos "PseudosTM_pwteter/13al.pspnc, PseudosTM_pwteter/33as.pspnc"

#%%<BEGIN TEST_INFO>
#%% [setup]
#%% executable = abinit
#%% [files]
#%% files_to_test = 
#%%   t58.out, tolnlines = 0, tolabs = 0.000e+00, tolrel = 0.000e+00, fld_options = -medium 
#%% [paral_info]
#%% max_nprocs = 2
#%% [extra_info]
#%% authors = D. R. Hamann
#%% keywords = NC, DFPT
#%% description = 
#%%   Test of the strain perturbation with the GGA
#%%   Note that this test and the following one, 59,
#%%   address more advanced features of strain perturbation than the ones
#%%   going with number 60 to 79, and were developed later, but were
#%%   placed here for convenience).
#%%   AlAs in the zincblende structure, with a choice of
#%%   pseudopotenials that include model core charges.  In the LDA, the
#%%   strain perturbation simply introduces perturbing charge densities
#%%   leading to perturbing first-order potentials in a straightforward
#%%   manner.  (This perturbation does act differently on the valence
#%%   and model core charges.)   The GGA is a non-trivial extension,
#%%   since strain perturbs the gradient operator itself.  This test
#%%   is a symmetrized and stripped-down version of a test case used in
#%%   development which yielded agreement between such RF calculations
#%%   and numerical derivatives of GS stresses and forces to 1.e-8 to
#%%   1.e-9 atomic units for the elastic tensor and intenal strain
#%%   coupling parameters.  Acheiving this agreement does require forcing
#%%   a considerably more dense fft grid than the default which is
#%%   accepted here. (ngfft= 50 50 50 was used.)  While only the PBE GGA
#%%   is tested here, all forms present in Abinit should give comparably
#%%   accurate results.
#%%<END TEST_INFO>