L-alanine requires more insight in terms of the optoelectronic properties as the organic devices. For that an electronic structure of the L-alanine using the density of state (DOS) and band structure have been calculated by the density functional theory (DFT) using the plane wave method. The unit cell crystal, single molecule and hydrogen bonding approach were investigated first in this work using GGA-PAW. The molecular orbitals were also examined using BL3YP functional for the hydrogen bonding between the amine and the carboxylic groups and found the bandgap energy comparable to the GGA-PAW case. The indirect band gap was obtained in the band-structure calculation. The effect of three linear molecules in x, y and z direction in a crystal was investigated and the significant variations found in DOS in all three cases of L-alanine. The present study predicted the longer length wire or tube structures are most useful as the outcome to make the good organic optoelectronic material.

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The coherent crystalline domain Size of a particle is well understood and investigable from the broadening of XRD peaks by Williamson-Hall (WH) method in connection with a strain, and it has a close correlation with the strain, stress, energy density, defects/dislocations. The coherent domain size of binary semiconducting material particles is being interlinked with the applications like sensors, solar systems, photo-detectors, photocatalyst etc. In the present work, the frustrated cluster of PbS elucidated the perspective of different models of the WH method. Frustrated microstructural PbScluster was prepared, confirmed and rendered its microstructural analysis from the XRD data and SEM. Eight various approaches as the variant models of the Williamson Hall plotting methods have been tested. It includes the models like Balzar approach, UDM, UDSM, UDEDM, modified WH model, Ehkl/E0ratio model, Direct fitting of simplified WH model with introducing new approach and the modified Kibasomba-WH model which uses linearization of Scherrer equation with the WH method. Present work lightens the USDM and UDEDM sizes in an account of a Zener constant. The other non-WH methods like the Scherrer formula method, modified Scherrer method, Stress-Strain methods and Halder-Wagner method are also included for comparison and to see their status in a cluster of frustrated structures. The sizes in connection with strain, stress, energy density, dislocation and stacking fault, have been also investigated for the frustrated PbS cluster.

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