A comprehensive first principles study of III-Antimonide binary compounds is hardly found in literature. We report a broad study of structural and electronic properties of boron antimonide (BSb), aluminium antimonide (AlSb), gallium antimonide (GaSb) and indium antimonide (InSb) in zincblende phase based on density functional theory (DFT). Our calculations are based on Full-Potential Linearized Augmented Plane wave plus local orbitals (FP-L(APW+lo)) method. Different forms of exchange-correlation energy functional and corresponding potential are employed for structural and electronic properties. Our computed results for lattice parameters, bulk moduli, their pressure derivatives, and cohesive energy are consistent with the available experimental data. Boron antimonide is found to be the hardest compound of this group. For band structure calculations, in addition to LDA and GGA, we used GGA-EV, an approximation employed by Engel and Vosko. The band gap results with GGA-EV are of significant improvement over the earlier work.

An orifice flow system has been developed indigenously which is a primary standard for the calibration of high vacuum gauges in the range of 10(-3)-10(-6) mbar. It consists of a constant-volume flow meter, designed to generate a known flow rate of a particular gas to the vacuum chamber. This chamber is partitioned into two parts by a plate with an orifice of calculable conductance. The pressures, generated by this standard system, are compared with those of secondary standard, namely, spinning rotor gauge. Different uncertainties and correction factors are calculated. The maximum percentage deviation is from 1.16% to 0.97%. The combined uncertainties over the entire calibration range of the standard system are in the range of 4.0 x 10(-6) mbar.

According to General Relativity (GR) the shape of spacetime determines the motions and paths of massive as well as mass-less particles. K -Surfaces play very important role in GR. Paths of the elementary particles are discussed by using the techniques of foliation of Schwarzschild spacetime by K-Surfaces and Isometric Embeddings.

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At low four-momentum transfer squared 0.02 < −t < 0.2 (GeV/c)2, we use the Chou–Yang model to predict the form factor of protons from proton–proton elastic scattering at center-of-mass energy s = 8 TeV. By fitting differential cross-sectional data from the TOTEM experiment to a single Gaussian, the form factor is extracted. We use this form factor to find the rms matter radius of the proton to be 0.88 fm, which is in good agreement with the experimental data and the theoretically predicted values of the rms radius.