[Wien] A basic problem about KGEN(shift k-mesh?)

[W Hx]

Dear users,
     In "WIEN2k-FAQ: KGEN: Add inversion ? Shift k-mesh ?"
	* "shift"the k-mesh ? (only for some lattice types) 
	* "Shifting" of k-mesh means that it will add (x,x,x) to all generated k-points, thus shifting them from high symmetry points (lines) to more "general" points with a higher weight. By this procedure (known also as "special k-point methods") one generates an equally "dense" mesh, but with less basis points. 
	* Usually a shift is recommended . Only one word of warning: When you are interested in "gaps" of semiconductors, they are often located at Gamma or X (or at some other BZ-border point). With shifted meshes you will NOT have those high-symmetry points in your mesh, thus the gap may seem to be smaller/larger than expected. 
	* Solution to this problem: Do the scf cycle with the shifted mesh, but for a DOS change to a fine unshifted mesh. 
From that we know that shifting of k-mesh generates an equally 'dense' mesh. So we should get nearly the same results for the same case whether shift k-mesh or not.
I calculated the same case (TiO2 2*2*2 supercell) with shift k-mesh and no shift k-mesh. But the ENE are different.
grep :ENE 222.scf_mini (shift k-mesh?    Yes)
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63765571
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63322019
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63804051
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63815033
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63855011
 
grep :ENE 222.scf_mini(shift k-mesh?    No)
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63642529
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63182990
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63679565
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63690506
:ENE  : ********** TOTAL ENERGY IN Ry =       -32144.63730723

The energies are different widely. I can not understand. 
For other case i minimized the struct with shift k-mesh and then run a cycle with no shift k-mesh, the energy may be larger or smaller. And the forces are not smaller than 2.
Can you explain it for me? Thank you for your time and patience.
yours sincerely,
Hongxia Wang
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