[Wien] accuracy problem after running x sgroup

[shamik chakrabarti]

Dear wien2k users,

                            we have done structure optimization (both volume
and force) of a A2BCO4 type material. After optimization the maximum force
on an atom is *2.036 mRy/a.u.* After optimization if we view the structure
with xcrysden we can see that some atoms remain unbonded i.e. one or two
free atom and the rest of the structure is connected through bond. Now my
questions are:

          (1) Can such a structure be stable although DFT has able to found
a solution in which the energy of the unit cell and forces on the atoms are
minimum?

          (2) When I take this optimized struct file and tried to initilize
and run a SCF with this struct file, after *x sgroup* command it will show :

                                                     *Accuracy problem.
Please run with different tolerance (x sgroup -settol .00000100)*
*
*
              Now if we ignore this problem or we run the command x sgroup
-settol 0.00000100, irrespective of that all the atoms got deleted after x
symmetry command!!

              So, my question is whether this optimized struct file is not
feasible or is their any way to remove this accuracy problem?

any response will be very helpful for us. Thanking you,

with regards,


-- 
Shamik Chakrabarti
Research Scholar
Dept. of Physics & Meteorology
Material Processing & Solid State Ionics Lab
IIT Kharagpur
Kharagpur 721302
INDIA
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