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10:04:45 AM PDT  Thu, Mar 24th 2016 

Dear NWChem developers,
When I trying optimize interatomic distant for Al 2 atoms claster starting from different points I get 2 different extrema: staring from 1.5 A gives interatomic distant 2.563 A with minimal Tot DFT E= 484.755378 (DFT b3lyp/631G**) while starting from initial distant 5 A gives interatomic distant 3.062 A with Tot DFT E=484.767366227. Changing the theory level does not help: the two extrema remain.
As I found out scanning the PES the problem arises because of the brake on the curve at the distant of approximately 2.91 A and two extrema at the left and at the right from the break. This type of PES takes place only if one would scan it by means of making single points energy calculations starting each time from initial guess. But if instead of it you will load vectors from the previous point of calculation the PES becomes smooth with only one extremum.
It looks like standard optimization algorithm at each step of optimization starts SCF from initial guess and does not use vectors from the previous step. How it can be changed?
Thank you.



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