Structure and Properties of a (CdSe)₆@(CdSe)₃₀Cluster Doped with Mn Atoms

Abstract

The structure and properties of a (CdSe) 6 @(CdSe) 30 cluster doped with one or two Mn atoms are studied using density functional theory. Geometrical structure optimizations are performed using relativistic effective core potentials for Se and Cd atoms and with an all-electron description for Mn atoms. The (CdSe) 6 core corresponds to a zinc blende bulk-type structure and each shell atom is connected to three atoms of the opposite type. We considered different Mn-substitutions of a single Se and Cd atom, substitutions of two Cd atoms with two Mn atoms, as well as additions of one and two Mn atoms to the (CdSe) 6 @(CdSe) 30 cluster. We found that an antiferromagnetic singlet state of the Mn 2 Cd 4 Se 6 @(CdSe) 30 cluster possesses the Fermi contact coupling constants which are close in the absolute value to the experimental ESR value. In the Cd-substituted clusters, the binding energies of Mn atoms are found to be appreciably larger than the binding energies of Cd atoms in the initial cluster, which explains the high miscibility of Mn in bulk CdSe. Experimental observations of drastic changes in the magnetic behavior of Mndoped Q-dots after the annealing can be explained from the results of our calculations of total energy as a function of total spin.

Spectral signatures of semiconductor clusters: (CdSe)16 isomers

“…It was found in previous studies that the states of semiconductor (AB) n clusters with fullerene-type geometrical structures typically possessed the lowest total energies for n < 29 whereas the states with core-shell geometrical structures became energetically more favorable for larger n. An exception is the (CdSe) 13 cluster with a single Se atom as a core. As for the (CdSe) 16 cluster, different geometrical structures have been found for its ground state in previous studies.…”

“…In order to test the reliability of the chosen BPW91/cc-pVDZ-pp approach, we performed optimizations [13] of the ground singlet state of a CdSe dimer using the coupled-cluster method with singles and doubles and non-iterative inclusion of triples [CCSD(T)] [32] and a larger cc-pVTZ-pp basis sets. The equilibrium bond distance r e and harmonic vibrational frequency ω e obtained at the BPW91/ccpVDZ-pp level of theory are 2.368Å and 261.0 cm −1 , respectively.…”

“…In both studies, the (CdSe) n clusters with n ≤ 5 have been found to possess ring geometrical structures whereas the energetically preferred geometrical structures in the range of n ≤ 6-16 are three dimensional spheroids. On the basis of DFT calculations, neutral (CdSe) n clusters have been predicted to possess core-shell structures for n = 13, 29-35 [12] and n = 36 [13].…”

Microwave assisted robust aqueous synthesis of Mn2+-doped CdSe QDs with enhanced electronic properties

“…But doping of CdSe QDs by Mn 2+ ions is a challenging job even though it has the comparable bulk solubility of approximately 50% like others. Self-purication is alleged for this difficulty due to wurtzite crystal phase of CdSe as emphasized by Erwin et al 17,18 The main factors which determine the doping efficiency are surface morphology, shape of the particles, and surfactants in the growth solution. Most of the synthesis techniques for Mn 2+ doped CdSe QDs have been reported for the high-temperature non-aqueous method using hazardous organometallic precursors.…”

The biaxial strain induced properties of ReX2 and ReXS (X = S, Se, Te) monolayers

“…When the transition metal disulfide changes from a bulk material to a two-dimensional structure, the band structure of the electron changes from an indirect band gap to a direct band gap, this will greatly change the optical propertise and electrical properties of the transition metal disulfide [8,9]. Not only that, but in many studies, the structure is doped with other atoms, and many good properties have been discovered, especially in terms of optoelectronic properties [10]. Associate Professor Xu Hua of Shaanxi Normal University adopted a bottom-up CVD growth method with ReO 3 , S powder and Se powder as precursors, and successfully prepared a single layer of 1T′ ReS 2 xSe 2 (1−x) with a series of different components for the first time [11].…”