About
9000 structures of magnesium clusters Mg
n
(n = 2–13) generated via different
methods were optimized at the DFT levels in order to estimate the
number of all possible stable structures that can exist for the given
cluster size (∼820,000 PES points were explored in total).
It was found that the number of possible cluster isomers N quickly grows with a number of atoms n; however,
it is significantly lower than the number of possible nonisomorphic
graph structures, which can be drawn for the given n. At the DFT potential energy surface, we found only 543 local minima
corresponding to the isomers of Mg2–Mg13. The number of isomers obtained in the DFT optimizations grows with n approximately as n
4, whereas
the N values extrapolated to the infinite generation
process grow as n
8. The cluster geometries
obtained from the global DFT optimization were then used to adjust
two empirical potentials of Gupta type (GP) and modified Sutton-Chen
type (SCG3) describing the interactions between the magnesium atoms.
Using these potentials, the extensive sets of structures Mg2-Mg55 (up to 30,000 clusters for each n) were optimized to obtain the dependence of the cluster isomer count
on n in the continuous range of n = 2–30 and for selected n up to n = 55. It was found that the SCG3 potential, which is closer
to the DFT results, gives a number of possible isomers growing as
approximately n
8.9, whereas GP potential
results in the n
4.3 dependence.
A new method for the electrodeposition of copper on oxidized aluminum alloys to form electrolytic coatings exhibiting high performance properties has been discussed. The effect of an azo compound-methyl red (MR)-additive on the structure and physicomechanical properties of the copper coatings formed on oxidized aluminum has been studied. Samples of aluminum alloys AD1M and AMg6BM have been subjected to an anodic treatment under identical conditions in two oxidation electrolytes of different compositions. Copper has been electrodeposited on oxidized aluminum alloy samples using a standard copper plating electrolyte. Comparison with a copper plating electrolyte of an identical composition with an MR azo dye additive has been conducted. The microstructure and adhesive properties of the copper coating formed on oxidized aluminum alloys have been studied. The relationship between the physicomechanical properties of the copper coating (microhardness, open porosity, adhesion) and the action of an azo dye additive in the copper plating electrolyte has been studied. The use of this technology will make it possible not only to increase the reliability and durability of machine parts and mechanisms but also to restore old parts and mechanisms.
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