#Driver

atom  1  # The basin of attraction of Oxygen atom will be examined
crit  2  # determine the critical points
surf  1  # build the Bader surface
gpsurf 1  # output for GNUplot
irho  1   # drives the integration of the Bader charge

#Parameter

# nsa 2  #  one might gain a bit of cpu time
# nsb 2  #  by using these values, smaller than the default
# nsc 2

inpt 50      # This value is suitable
ntheta 8    # This value is much too small
nphi 4       # This value is much too small
thetamax   3.14159265358  # These two variables define a quadrant
phimax   1.57079632679    #
  maxatd 10.9   # The starting atoms within this distance are sufficient
  maxcpd 8.0
  lgrad2 1.0d-4  # Such loose criteria are needed to catch all the CPs.
  lstep2 1.0d-4  #
  dpclim 5.0d-2  # Because the ecut is quite low, the finite elements
                 # are quite large. So, it might be that ONE critical point
                 # is seen on TWO finite elements, while being at a larger
                 # distance that the default value of dpclim

#%%<BEGIN TEST_INFO>
#%% [setup]
#%% executable = aim
#%% test_chain = t32.in, t33.in, t34.in
#%% [files]
#%% files_to_test = 
#%%   t33.out, tolnlines = 19, tolabs = 2.000e-03, tolrel = 2.000e-04, fld_options = -medium
#%% psp_files = DensityCore_pw/08-O.8.fc, DensityCore_pw/12-Mg.8.fc
#%% [paral_info]
#%% max_nprocs = 1
#%% [extra_info]
#%% authors = Unknown
#%% keywords = 
#%% description = 
#%%   MgO molecule, Bader analysis.
#%%   Examine the Oxygen atom only.
#%%   Determine 2 bonding critical points (only !),
#%%   8 ring critical points, and 8 cage critical points.
#%%   (In agreement with Euler's relation : #BCP-#RCP+#CCP=2)
#%%   The ecut that was used in test case 32 is quite
#%%   low, so that the accuracy of the critical points is not
#%%   too good. Especially, symmetries are broken at the level
#%%   of 0.0003.
#%%   Get 2 core electrons, 6.8043 valence electrons.
#%%   The nucleus charge is +8. The Oxygen atom-in-molecule
#%%   has a net charge of -0.8043.
#%%   Additional explanation about the weak number of BCP
#%%   for oxygen. One might expect the O atom to be connected
#%%   through the other O atoms in neighbouring cells (x and y
#%%   directions - hence 4 BCPs in these directions), but
#%%   one sees that the only existing BCPs
#%%   are towards the Mg atoms. This is surprising, but correct ! Indeed,
#%%   the density at the middle of the segment between two O atoms
#%%   along x (or y) is LOWER than the density at the
#%%   middle of the segment between two Mg atoms along x (or y).
#%%   Indeed, although the O atoms attract electrons from the Mg
#%%   atoms, they become negatively charged, and the potential,
#%%   in DISTANT regions of the molecule, is lower (so more
#%%   attractive) on the side
#%%   of the Mg atoms than on the side of the O atoms !
#%%   This means that the tail of the density extends further
#%%   in the x-y plane containing the Mg atoms, than in the
#%%   x-y plane containing the O atoms. So, the middle of the
#%%   segment connecting the O atoms actually belongs to the
#%%   Mg basin of attraction, and is close to a Cage Critical Point
#%%   shared by Oxygen and Magnesium atoms. By contrast, the
#%%   middle of the segment connecting the Mg atoms is, as expected,
#%%   close to a Bond Critical Point.
#%% topics = Bader
#%%<END TEST_INFO>