Pyramidal defects in Mg-doped GaN in light of strain-energy minimization

2011 ◽  
Vol 99 (24) ◽  
pp. 241905 ◽  
Author(s):  
Dong Nyung Lee
Keyword(s):  
Energy Minimization ◽  
Strain Energy ◽  
Strain Energy Minimization ◽  
Mg Doped

Anionopentaaminecobalt(III) complexes with polyamine ligands. XIX. Computer simulated intermediates for dissociative aquation reactions

1984 ◽  
Vol 37 (2) ◽  
pp. 239 ◽  
Author(s):  
DA House ◽  
RGAR Maclagan
Keyword(s):  
Ground State ◽  
Rate Constants ◽  
Energy Minimization ◽  
Strain Energy ◽  
Essential Role ◽  
Energy Difference ◽  
Total Strain Energy ◽  
Dissociative Mechanism ◽  
Approximate Order ◽  
Strain Energy Minimization

Strain energy minimization calculations have been performed for several octahedral chloropenta-amine cobalt(III) complexes with polyamine ligands. Similar calculations on the five-coordinate residue obtained by removal of the chloro ligand allow an estimation of the geometry and energy of a potential intermediate in a chloride release reaction proceeding via a dissociative mechanism. In all cases the five-coordinate residue is less strained than the six-coordinate octahedron and the non-replaced ligands play an essential role in determining the resulting distortion. Thus for the series mer-CoCl(NN)(dien)2+ (NN = en, (NH3)2,tn), the total strain energy difference between the minimized ground state and the minimized five-coordinate residue is 12.2, 18.3 and 25.8 kJ mol-1, respectively. This order is identical (where data are available) to that of the rate constants (and activation energies) for thermal aquation, Hg2+ assisted aquation and mer → fac-dien isomerization in this series. Similar calculations have been performed for a series of trans-CoCl2(N4)+ systems and again the energy differences are in the approximate order of the rates of thermal aquation. In the case of N4 = (NH3)2, the energy difference between trans-and cis-CoCl(NH3)4(OH2)2+ products is about 1 kJ mol-1, the trans-isomer being the more stable.

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