The Peculiarities of Americium Electronic Structure and Magnetic Susceptibility

Electron heat capacity and lattice properties of Americium

“…In accordance with earlier calculations of the mag netic susceptibility of americium [10], the correlation radius = (a (l) D (l) ) 1/2 of spin density of f and d elec trons (where a l (~ 0.1) is the spatial inhomogeneity parameter of the Lindhard function) above = 75 K and = 45 K, respectively, turns out to be not larger than the interatomic spacing. As a result, we can disre gard interstitial spin density correlations in the system of f and then d electrons at T > and then at T > , and term in Eq.…”

“…It was shown earlier that noticeable spin fluctuation effects appear in calculations of the elec tronic structure and the spin magnetic susceptibility in the strongly correlated subsystem of d, f electrons in americium [10], which must make a significant con tribution to the formation of its electron heat capacity.…”

“…(3) in the energy units (i.e., is multiplied by the Boltzmann constant in electronvolts, which is equal to 0.8625 × 10 -4 eV/K); 2n l is the filling factor of the l band; and = is the mean square of the modulus of the random onsite exchange field (see [10,11]). The contribution to the TDP associated with para magnons and their interaction has the form (3) where…”

“…(μ + αIm (l') ); and m (l') is the squared amplitude of spin fluctuations, which is calculated using the fluctu ation-dissipation theorem [10,11].…”

“…The expression for volume thermal expansion coefficient O and bulk modulus K obtained in such an approach on the basis of the phonon contribution to TDP (1) have the form (6) (7) Parameters γ θ and appearing in these relations are the generalized Grüneisen parameters [12], and the Debye temperature is calculated by the formula (8) where μ is the molar mass; K is the bulk modulus; V is the molar volume; ប, k B , and N A are the Planck and Boltzmann constants and the Avogadro number; and Θ is an auxiliary function depending on Poisson ratio σ characterizing the ratio of shear modulus G to bulk compression modulus K. Figure 1 shows the electron heat capacity obtained from self consistent calculation of the density of elec tron states and spin magnetic susceptibility [10]. It can be seen that the paramagnetic contribution increasing in the spin fluctuation temperature interval, which is responsible for the peak in the electron heat capacity, is significant in the low temperature range.…”