Spin-free frozen-core approximation

The frozen core approximation was tried by Brooks, Johansson and Skriver (1984) in calculations of E for some actinides and refractory actinide compounds. It turned out that unless further improvements were made, the calculations failed to reproduce the observed regularity of the cohesive energy changes in the actinide series. Because of this, a semi-empirical method was proposed to determine corrections to the calculated values of j determined by the spin state of free atoms. This method allowed the reproduction of the experimental regularities by which ,.<,1, changes in the actinide series and in transition 3d-, 4 - and 5d-metals. 

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