<div dir="ltr">Dear wien2k users,<div><br></div><div> We have optimized atomic coordinates of a spinel cubic compound containing 56 atoms/cell. The most important variation we have seen between experimental structural coordinates & DFT (GGA+U) optimized coordinates is that.</div><div><br></div><div>the oxygen coordinate changes from (x,x,x) configuration to (x,y,z) configuration as we have not constrained the oxygen coordinates during optimization.</div><div><br></div><div>Although, this change has generated a structure having very small forces (< 1 mRy/Bohr) per atoms, the change in oxygen coordinates are significant (difference between x & z is 0.021) enough to change the relative intensities of different peaks of XRD patterns. </div><div><br></div><div>Now my query is (before starting the experimental simulation by myself again!!) whether there is a way to constrain atomic coordinates such that it remain constrained to (x,x,x) configuration while changing the value of x?</div><div><br></div><div>& also whether such a constrained way should be adopted or should we accept the DFT optimized structure (a bit different from experimental one!!) as it is for further calculation?</div><div><br></div><div>Looking forward to your opinions & suggestions.</div><div><br></div><div>Thanks in advance,</div><div><br></div><div>with regards, <br clear="all"><div> </div>-- <br>Shamik Chakrabarti<br>Senior Research Fellow<br>Dept. of Physics & Meteorology<br>Material Processing & Solid State Ionics Lab<br>IIT Kharagpur<br>Kharagpur 721302<br>INDIA
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