yes generally GGA calculated lattice values tend be higher than LDA ones and there might be differences in the values because of different simulation packages that people use.... thanks for the code snippet.
But i still don't understand how the bond lengths will change on rotation as i only change the angle and even after rotating about y axis (say, 1degree,2 degree and so on..) i have checked in z-matrix the bond lengths remains the same as selected earlier.
see the attached image( 0 degrees and after rotation by 10 degrees )as the second atom gains some 'z ' coordinate as well
pls note i just calculated energy at each such 'new points' after rotation steps without including any kind of optimization.
Thanks for all the help given by forum members and moderators..and yesss wishing a very happy new year