Electric Dipole (Hyper)polarizabilities of Selected X₂Y₂ and X₃Y₃ (X = Al, Ga, In and Y = P, As): III−V Semiconductor Clusters. An ab Initio Comparative Study

Abstract

A systematic ab initio comparative study of the (hyper)polarizabilities of selected III-V stoichiometric semiconductor clusters has been carried out. Our investigation focuses on the ground state structures of the dimers and on two dissimilar trimer configurations of aluminum, gallium, indium phosphide and arsenide. The basis set effect on both the polarizabilities and hyperpolarizabilities of the studied systems has been explicitly taken into account relying on the augmented correlation consistent aug-cc-pVnZ (n = D, T, Q, and 5) basis sets series. In addition, a rough estimation of the effects of the relativistic effects on the investigated properties is provided by extension of the study to include calculations performed with relativistic electron core potentials (or pseudopotentials). Electron correlation effects have been estimated utilizing methods of increasing predictive reliability, e.g., the Møller-Plesset many body perturbation theory and the couple cluster approach. Our results reveal that in the considered semiconductor species the Group III elements (Al, Ga, In) play a vital role on the values of their relative (hyper)polarizability. At all levels of theory employed the most hyperpolarizable clusters are the indium derivatives while the aluminum arsenide clusters also exhibit high, comparable hyperpolarizabilities. The less hyperpolarizable species are those composed of gallium and this is associated with the strong influence of the nuclear charge on the valence electrons of Ga due to the poor shielding that is provided by the semicore d electrons. In addition, the analysis of the electronic structure and the hyperpolarizability magnitudes reveals that clusters, in which their bonding is characterized by strong electron transfer from the electropositive to the electronegative atoms, are less hyperpolarizable than species in which the corresponding electron transfer is weaker. Lastly, from the methodological point of view our results point out that the hyperpolarizabilities of those species converge when an augmented triple-zeta quality basis set is used and, also, that the second order Møller-Plesset approximation (MP2) overestimates considerably their second hyperpolarizabilities with respect to the highest level of coupled cluster theory applied in this study (CCSD(T)).

On the shape dependence of cluster (hyper)polarizabilities. A combined ab initio and DFT study on large fullerene–like gallium arsenide semiconductor clusters

“…As it has been shown in a previous study [15], the inclusion of electron correlation effects though the CCSD(T)/aug-cc-pVDZ level of theory on the calculation of the mean polarizability of Ga 2 As 2 returns a value which is <5% than the HF value. A similar picture is observed in the case of the second hyperpolarizabilities (Fig.…”

Origin of the size-dependence of the polarizability per atom in heterogeneous clusters: The case of AlP clusters

“…[2][3][4][5][6][7][8][9][10][11][12] An interesting approach to study the properties of these systems is to analyze how their properties in gas-phase vary with their aggregation number and converge to those of the bulk material. [2][3][4][5][6][7][8][9][10][11][12] An interesting approach to study the properties of these systems is to analyze how their properties in gas-phase vary with their aggregation number and converge to those of the bulk material.…”

“…2,12 This deviation of the properties of the clusters from those of the bulk material at the smallest cluster sizes is usually referred to as the "size effect." [13][14][15][16][17] In addition, for the medium size clusters, the PPA fluctuates around the bulk value both in semiconductor clusters [2][3][4][5][6][7][8][9][10][11] and in metals. [13][14][15][16][17] In addition, for the medium size clusters, the PPA fluctuates around the bulk value both in semiconductor clusters [2][3][4][5][6][7][8][9][10][11] and in metals.…”

“…Recently, Karamanis et al [7][8][9][10] studied the polarizabilities of stoichiometric Al n P n clusters, attributing the evolution of the PPA in the function of n to two effects, namely, the size effect and the bonding effect. While the size effect refers to the rapid decrease of PPA in clusters containing less than six atoms, which is, as mentioned above, also typical for small metallic clusters, the bonding effect explains the fluctuations in the PPA curve for the larger aggregation numbers in terms of the nature of the bonds between the different atoms.…”

“…Karamanis et al [7][8][9][10] analyzed the evolution of the PPA curve in the function of the cluster size in terms of the global polarizabilities of the clusters. In the present work, we undertake to analyze this phenomenon further by computing the polarizabilities of the phosphorus and aluminum atoms within the clusters.…”