Nonlinear optical properties of CdSe clusters have been investigated using time dependent density functional theory. Finite and negative values of static and frequency dependent first order hyperpolarizability have been observed in case of CdSe and Cd3 Se3 while the same is absent in Cd2 Se2 and Cd4 Se4. At specific frequencies, sudden increase in the frequency dependent components of first order hyperpolarizability tensor (second harmonic generation) has been attributed to the near resonance of the input energy. Three components of second order hyperpolarizability tensor have been calculated by combining analytical and finite difference techniques. The results indicate that these clusters have a high degree of nonlinear optical properties. © 2006 The American Physical Society.

S SEN

S CHAKRABARTI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

&nbsp;

The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

&nbsp;

It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Physical Review B - Condensed Matter and Materials Physics

We report herein the numerical analyses on the nonlinear optical properties of CdnTen clusters up to decamer unit. A detailed study on the static and frequency dependent response properties of these CdnTen clusters has been performed employing density functional approximations of different levels. Our investigation reveals that both static and frequency dependent second order hyperpolarizability tensors of these clusters are significantly high (103-107 a.u.) in magnitude. The first order counterpart is also high for certain cluster size. We observed that the response properties are highly structure-dependent and is particularly noticeable in higher clusters. © 2009 Elsevier B.V. All rights reserved.

Chemical Physics

Ab initio investigation on the nonlinear optical properties of CdnTen (n = 1-10) clusters

We report results of hyperpolarizability calculations on CdnXn (X: S, Se and Te; n = 1-10) clusters. Our results show that the geometric configurations of different types of clusters under investigation are quite similar at specific values of n. Both static and frequency dependent components of first and second order hyperpolarizability tensors of CdnSn, CdnSen and CdnTen are compared. It is observed that in general nonlinear optical coefficients show identical variation in all the cluster materials. The present investigation also manifests the improvement of these coefficients due to the introduction of asymptotically correct generalized gradient approximation functional over the local density functional and normal gradient corrected functional. Symmetrized fragment orbital analysis has been performed to provide explanation of the observed hyperpolarizability variation. We also analyse how geometries with closely lying energy values influence the hyperpolarizabilities of these cluster materials. © 2010 Springer Science+Business Media, LLC.

Journal of Cluster Science

A Comparative Study of the Nonlinear Optical Properties of CdnXn (X: S, Se and Te) Clusters

Density functional theoretical calculations have been performed on small and medium-sized (CdSe)n (n = 1-16) clusters in order to evaluate the variation in electric polarizability and anisotropy in polarizability with increase in the cluster size at both static and Nd:YAG laser frequencies. The electric polarizability values at static frequency show a rapid decrease up to heptamer only with the exception observed for (CdSe)5 clusters where a sudden increase in the polarizability value is observed. An even-odd oscillating behavior is observed in the anisotropy values between the dimer and heptamer CdSe clusters. Apart from polarizability and anisotropy calculations, the variation in the energy gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital and second difference of energies with the cluster size have also been calculated. Just like the anisotropy values, an even-odd oscillating behavior is also observed in the second difference value for the smaller CdSe clusters. © 2008 Elsevier B.V. All rights reserved.

Computational Materials Science

Static and dynamic polarizabilities of (CdSe)n (n = 1-16) clusters

Static and dynamic hyperpolarizability calculations have been performed to explore the nonlinear optical properties of aluminum metal clusters Al4 M4 (M=Li, Na, and K). An analytical approach combined with a finite difference technique has been used to evaluate the response properties within the framework of time-dependent density functional theory. Components of the first and second order hyperpolarizability tensors are estimated in the vicinity of excitation frequencies with substantial oscillator strength. At specific frequencies, large values of first and second order hyperpolarizability tensors reveal the importance of these materials as cluster with very large optical nonlinearity. The analysis of gross populations of molecular orbitals with the most significant symmetrized fragment orbitals indicate that except for Al4 K4 [two-dimensional (2D) and (3D)] and Al4 Li4 (3D) there exists excitations other than charge transfer interaction which can also lead to high nonlinear optical coefficients. © 2007 The American Physical Society.

Static and dynamic hyperpolarizability tensors of aluminum metal clusters, Al4 M4 (M=Li, Na, and K)

The effects of charge transfer and molecular chain length on the electrical polarizability of doped trans-polyacetylene oligomers have been investigated using a series of quantum chemical methods ranging from Hartree-Fock to current density functional theory. Polarizability tensors of pristine and metal-doped trans-polyacetylene oligomers have been estimated. The nature of variations of polarizability tensor components are quite different for pristine and doped oligomers. For doped samples, distinct minima in the average static polarizabilities per acetylene unit have been observed. The results suggest that the competitive role of charge-transfer interaction and oligomer chain length are responsible for the observed minima. To simulate the ab initio results on polarizability variation, we propose a mathematical model that describes the minima quite satisfactorily. © 2007 American Chemical Society.

Journal	Physical Review B - Condensed Matter and Materials Physics
Publisher	AMER PHYSICAL SOC
ISSN	1098-0121