<div dir="ltr">Dear Johannes, I think this is due to the initialisation of the atomic velocities which is eventually based on pseudo-random numbers. If you switch two atoms in the list, then you switch also their initial velocities and their positions will be different in the next MD step. Consequently the total energy will be different, tool. The pseudo-random numbers are deterministic and thus for the same atomic sequence the result is reproducable, if you alter the sequence, however, this is no longer true. Matthias On Thursday, 5 March 2015 18:51:13 UTC+1, Johannes Wagner wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr">Dear all, maybe I am missing something but I recently had to realise that when I change the order of coordinates of my inpuf file in a FIST run, but leave anything else the same, I get another result (quite substantially from time to time) e.g. in the al2o3.inp from /cp2k/tests/Fist/al2o3.inp If I run this file for one step I get # Step Nr. Time[fs] Kin.[a.u.] Temp[K] Pot.[a.u.] Cons Qty[a.u.] UsedTime[s] 0 0.000000 1.768042507 298.000000000 -281.499021201 -279.730978694 0.000000000 1 3.000000 1.760113969 296.663661049 -281.491144428 -279.731030458 0.80785918 If I run it again, putting all the Oxygens and their coordinates first, I get # Step Nr. Time[fs] Kin.[a.u.] Temp[K] Pot.[a.u.] Cons Qty[a.u.] UsedTime[s] 0 0.000000 1.768042507 298.000000000 -281.499021201 -279.730978694 0.000000000 1 3.000000 1.777233556 299.549132838 -281.508050366 -279.730816810 0.802598953 Is this expected behaviour? Have I missed something? I am using the latest svn checkout. I figured since everything is index with the Atomic Kind, it shouldn't matter where in the coordinate list an atom appears, maybe this was wrong. If this is normal, what is the "correct" way of ordering the atomic coordinates? thank you all for any hints all the best, Johannes </div></blockquote></div>