Effects of Alloying Element Cr on Ni-Mn-Ga Alloys Studied by Ab Initio Calculations

The effects of Cr addition on the crystal structure, phase stability and magnetic properties of Ni8Mn4-xGa4Crx (x=0, 1 and 2) ferromagnetic shape memory alloys are systematically investigated by ab-initio calculations. The formation energy results indicate that the added Cr preferentially occupies the Mn sites in Ni2MnGa alloy due to the lowest formation energy. The evaluated Curie temperature decreases with increasing Cr content are derived from the decrease of the total energy difference between the paramagnetic and the ferromagnetic austenite.

Kinetic energy analysis of atomic multiplets. II. smdn configurations

A kinetic energy analysis of total energy differences in 822 atomic multiplets arising from smdn (m = 0,1,2; n = 2–8) electronic configurations is performed within the nonrelativistic, restricted Hartree–Fock framework. For the 444 multiplets arising from the dn and s2dn configurations of 27 atoms in groups 2–10, a very good linear correlation between the total energy difference and the kinetic energy difference of the outermost d-electrons is demonstrated. For the 378 multiplets arising from the sdn configuration, on the other hand, a good linear correlation is obtained provided that the multiplets are classified into groups based on spin multiplicity. Key words: kinetic energy, atomic multiplets, smdn configurations, Hartree–Fock approximation.

Cubo-Octahedral B12 Clusters In Silicon Crystal

A new stable structure and the electronic structure of boron clusters in silicon crystal have been calculated using the first-principles local density functional approach for Si54B12H60 clusters. According to our calculation, the cubo-octahedral B12 cluster was found to be more stable than the icosahedral one proposed previously. The total energy difference was about 4.6 eV. The analysis of the partial density of states showed that the cubo-octahedral B12 cluster should act as a double acceptor.

FIRST-PRINCIPLES CALCULATION OF THE MAGNETOCRYSTALLINE ANISOTROPY ENERGY FOR THE PSEUDOBINARY COMPOUND Y(Co1−xFex)5

From the experimental behavior of the magnetocrystalline anisotropy energies of the pseudobinary compounds Y(Co1−xFex)5, it has been argued that the magnetocrystalline anisotropy energies for YCo5 and the hypothetical compound YFe5 will have different signs. This anomalous behavior is attributed to the change of the number of 3d electrons and their orbital moments when proceeding from YFe5 to YCo5. The magnetocrystalline anisotropy energies are calculated using the linear muffin-tin orbital (LMTO) method in the atomic sphere approximation (ASA) including spin-orbit interaction and orbital polarization. The force-theorem is used to express the total energy difference (between the two directions of magnetization) as a difference in the sum of the single particle eigenvalues. We find that it is possible to predict the correct easy-axis for YCo5 and YFe5. Secondly it is found that the inclusion of orbital polarization is essential for the cobalt compound but less important for the iron compound. The different contributions from the two inequivalent transition metal sites to the anisotropy energy and orbital magnetization are discussed.

INCREMENTAL CHARGING OF A MOLECULE AT ROOM TEMPERATURE: DISTURBANCE OF MOLECULAR ELECTRONIC STATES DUE TO THE TUNNELING EVENT

The many-electron problem has been studied by many researchers, mainly theoretically. The reason why there have not been many experimental studies is that there have not been adequate tools to measure the total energy of a system. We have succeeded to measure the total energy difference between an ionized molecule and a neutral molecule. This answers the question of how much the correlation energy is. The measured total energy differences between the ionized state and the neutral state are far smaller than those which are calculated, even including the effect of the substrate on which the molecules are supported. This result provides a way of comparing theoretical and experimental values of the correlation energy.