Department of Chemistry

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Design of Novel Lanthanum Doped Al12P12 Nanocages with High Nonlinear Optical Response
(Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-20) Faiqa Khaliq; SP19-R06-022; Dr. Mazhar Amjad Gilani; LHR TP 6523
In current study, the effect of lanthanum doping over Al12N12 and Al12P12 nanocages has been investigated using density functional theory. The strong influence of lanthanum doping on geometrical, electronic, linear, and nonlinear optical properties of Al12N12 and Al12P12 nanocages has been observed. The results revealed that doped nanoclusters possess high thermodynamic stability upto -37.37 kcal/mol and HOMO-LUMO gap is reduced upto 0.89 eV. NBO analysis confirms the charge transfer from metal towards nanocage. The Partial Density of States (PDOS) and Total Density of States (TDOS) strongly support the formation of new HOMO energy level which contributes in the reduction of HOMO-LUMO orbital energy gap. Doping of lanthanum remarkably increases the first hyperpolarizability (βₒ) of the complexes. The highest first hyperpolarizability of 4.43 × 104 au is observed for La@endo-Al12N12 complex. The present investigations intrigue the designing of high performance NLO materials that can be beneficial for their use in modern optoelectronic applications.
A Comparative Study of Different DFT Functionals on the Nonlinear Optical (NLO) Properties of Some NLO Prototypes
(Library Information Services COMSATS University Islamabad Lahore Campus, 2020-02-19) Alina Waheed; SP19-R06-018; Dr. Mazhar Amjad Gilani; LHR TP 6521
he present study spotlights the fundamental insights about four different classes of functionals and their efficacy to calculate the nonlinear optical (NLO) and linear properties. For this study, urea and (p-NA) para-nitroaniline molecules are used up as reference organic molecules. For comparative analysis, there is a dire need of such database to be utilized by the researchers. We have reported a range of functionals including hybrid (B3LYP, PBE1PBE, BHandHLYP), meta-hybrid (M06, M06-2X, M06-HF, M06-L), long-range corrected (CAM-B3LYP, LC-BLYP, LC-B97D, LCB97D3) along with dispersion correction (ωB97, ωB97X, ωB97XD, HSEH1PBE). These groups are evaluated and their efficiency to calculate linear and NLO properties is graphically compared with each other. NLO properties including anisotropic and linear isotropic polarizabilities, dipole moment, second- and third- order polarizabilities were analysed using their corresponding groups and there functionals. The presented results will help researchers to compare their calculations for the properties of NLO in different species. The current study highlights the importance of different functionals and their methods to be employed on various organic and inorganic species to study and evaluate their hyperpolarizabilities. The dipole moment of urea has been found to be 5.14 D which is close to experimentally determined value of 4.56 D. Similarly, the respective experimental and theoretical values of average second order polarizability as calculated by ωB97XD are quite close to each other. Interestingly, similar values of LC-B97D and LC-B97D3 for all the calculated parameters are obtained corresponding to urea and p-NA. A good agreement has been noticed among geometries, total electronic dipole moments and NLO polarizabilities on comparative basis. In addition, the (MEP) molecular electrostatic potential and (FMO) frontier molecular orbital map analyses are executed for the visual insight of charge transfer and predicting the reactive sites. In short, the current work provides significant methods to study the dipole moment, bond lengths, bond angles, static and frequency dependent second order and third-order polarizabilities. linear isotropic and anisotropic polarizabilities. Hence, the present results will attract the scientific community to compare their experimental work on various organic species with our results of urea and p-NA. These compounds are widely used as reference species in experimental and theoretical appraisal in the field x of nonlinear and linear optics. The current investigation will evoke scientific interest regarding the promising comparison of NLO properties in various organic species which can be beneficial in modern hi-tech applications.
Substitution of Alkali Metal Atoms: An Efficient Approach to Enhance Electronic and Nonlinear Optical Properties of Diamantane
(library Information Services CUI Lahore Campus, 2020-02-16) Palwasha Khan; SP19-R06-012; Dr. Mazhar Amjad Gilani; LHR TP 6515
Applications of nonlinear (NLO) materials in the fields like electronics, optics, optoelectronics, and optical computing, etc. drive the interest of many scientists to design high-performance NLO materials. Electronic properties, absorption spectra and nonlinear optical properties of alkali metal substituted diamantanes are presented. A significant reduction in HOMO-LUMO gap has been observed by alkali metal substitution. K@CHa has the lowest H-L gap of 1.64 eV as compared to 8.88 eV for pristine diamantane. A remarkable increase in the first hyperpolarizability (βₒ) has been observed due to the substitution of alkali metals. Among these structures, K substituted complexes show the largest first hyperpolarizability (25526-36328 a.u). This significant increase in the first hyperpolarizability (βₒ) is attributed to low crucial transition energies ΔE. K@CHa has the lowest ΔE value (2.0650 eV) which results in the highest βₒ value (36328 a.u.) for K@CHa. Furthermore, frequency-dependent hyperpolarizabilities calculations are carried out using 1906 nm, 1340 nm, and 1064 nm frequencies for commonly used lasers. This study provides an efficient approach to design high-performance NLO materials having extensive applications in the field of electronics and optoelectronics. The results reveal that substitution of alkali metals leads to the shift in absorption from ultraviolet to the visible

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