https://nepjol.info/index.php/HP/issue/feed Himalayan Physics 2024-05-24T07:52:22+00:00 Himalayan Physics himalphys@gmail.com Open Journal Systems <p style="font-weight: 400;"><em>Himalayan Physics (HimPhys)</em> is a distinguished, open-access, peer-reviewed journal dedicated to publishing high-quality articles that make innovative contributions to various fields of physics. It is published annually by the Nepal Physical Society (Gandaki Chapter) and the esteemed Department of Physics at Prithvi Narayan Campus in Pokhara. The primary objective of HimPhys is to provide a platform that unites researchers and practitioners from both domestic and international academic communities, fostering a focused exchange on advanced techniques and the exploration of new frontiers within the physical sciences. By facilitating collaboration and knowledge-sharing, HimPhys aims to establish strong connections with the vibrant physics community in Nepal.</p> https://nepjol.info/index.php/HP/article/view/62178 Lattice parameters prediction of orthorhombic oxyhalides using machine learning 2024-01-24T15:10:15+00:00 Poojan Koirala a@b.com Madhav Ghimire madhav.ghimire@cdp.tu.edu.np <p>Lattice parameters of orthorhombic oxyhalides with molecular formula AOX are predicted using KRR, LR, and GBR machine learning (ML) models. Seventeen data of orthorhombic oxyhalides are extracted from the Materials Project Database, and several features such as atomic radius, ionic radius, band gap, density, electro-negativity, and atomic mass are taken into account. After refining the data, they are used for ML training and testing processes. The actual values of the respective compounds' lattice parameters are compared with those predicted by different models. Then, the accuracy of their predictions is checked by calculating MAE, MSE, and R<sup>2</sup>. The GBR model is more efficient in predicting lattice parameters 'b' and 'c', whereas KRR is found to be more more efficient in predicting 'a'. Further, using the random forest regression model, the features importance plot is also observed to understand which features play an important role in predicting the lattice parameters.</p> 2024-01-24T00:00:00+00:00 Copyright (c) 2024 Himalayan Physics https://nepjol.info/index.php/HP/article/view/61269 Assessment of natural background radiation levels in Ranipokhari, Kathmandu, Nepal, following the 2015 earthquake and during reconstruction 2023-12-31T15:30:09+00:00 Hari Adhikari ahari7928@gmail.com Roshan Chalise plasma.roshan@gmail.com Himali Kalakhety hkalakhety@gmail.com Raju Khanal raju.khanal@cdp.tu.edu.np <p>Natural background radiation is present in the environment and its level can vary depending on the location, occurring radioactive elements in soil, water, and air. The measurement of natural background radiation in Ranipokhari, a historic pond in Kathmandu, is important as it is currently undergoing reconstruction after the 2015 earthquake. We used a Professional Digital Geiger Counter (GCA 07W) to measure the radiation dose at 50 different locations, 31 of which were on the outer corner of the pond and 19 were inside the pond. The minimum and maximum radiation exposure levels were found to be 49.80 μR/h and 147.48 μR/h, respectively, with an overall average exposure rate of (108.06 ± 3.47) μR/h. We observed that the count and exposure rates were higher on sunny days compared to rainy days. Hypothesis testing suggested that the average background exposure rate in Ranipokhari is higher than the world average external background radiation levels reported by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Our study provides crucial information on the natural background radiation levels in Ranipokhari, which can assist in the safe reconstruction of this historic pond after the earthquake.</p> 2024-05-12T00:00:00+00:00 Copyright (c) 2024 Himalayan Physics https://nepjol.info/index.php/HP/article/view/66159 From the Hamilton-Jacobi equation to the Schrödinger equation and vice versa, without additional terms and approximations 2024-05-24T07:52:22+00:00 J.D. Bulnes a@b.com M.A.I. Travassos a@f.com D.A. Juraev t@g.com J. Lopez-Bonilla joseluis.lopezbonilla@gmail.com <p>In this article, we will answer a question posed in the book Classical Mechanics by H. Goldstein: ``"Is the Hamilton-Jacobi equation the short wavelength limit of the Schrödinger equation?" But, before that, we will identify an essential element that will take us from the Hamilton-Jacobi equation to the dynamic equation of non-relativistic quantum mechanics for a function ψ through an exact procedure. This element is the linear independence of the functions ψ and ψ* (their complex conjugate). Their independence is demonstrated for physical systems where the acting physical potential does not explicitly depend on time. Proceeding in reverse, from the Schrödinger equation, we obtain the Hamilton-Jacobi equation, exactly, without additional terms.</p> 2024-05-24T00:00:00+00:00 Copyright (c) 2024 Himalayan Physics https://nepjol.info/index.php/HP/article/view/65329 First-Principles DFT Study of the Molecular Structure, Spectroscopic Analysis, Electronic Structures and Thermodynamic Properties of Ascorbic Acid 2024-04-30T17:54:31+00:00 Pima Gharti Magar pimagm100@gmail.com Roshika Uprety rosuuprety789@gmail.com Krishna Bahadur Rai krishna.rai@pmc.tu.edu.np <p>We present an analysis of the optimized geometry, vibrational spectroscopic frequencies, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap, global reactivity parameters, molecular electrostatic potential (MEP), electrostatic potential (ESP), electronic density (ED), density of states (DOS), Mulliken charges and thermodynamic properties of Ascorbic acid (C<sub>6</sub>H<sub>8</sub>O<sub>6</sub>) using the density functional theory (DFT) with B3LYP/6-311G(d,p) basis set. Various vibrational modes including C-C and C-H stretching vibrations were observed and identified. Along with these, in-plane C-H bending vibrations were also detected within the range of 3000-3100 cm<sup>-1</sup>. Analysis of the calculated HOMO and LUMO energies revealing insights into its chemical stability and reactivity and inform significant charge transfer phenomenon with an energy gap of 5.6545 eV between them within the molecule. The DOS spectrum provided additional clarity on the energy levels of orbitals, complementing with our HOMO-LUMO analysis. The global reactivity parameters i.e. hardness, chemical potential, electronegativity, chemical softness and electrophilicity index were determined to be 2.8272 eV, -3.9892 eV, 3.9892 eV, 0.3481 eV⁻¹ and 2.8143 eV respectively suggesting valuable information on its chemical reactivity and interaction potential. Visualizations of ESP, MEP and ED offered a deeper understanding of its molecular interactions and charge distribution. The Mulliken charges analysis indicated that most of the carbon atoms except C10 and all the hydrogen atoms show positive charge while all the oxygen atoms together with C10 show the negative charges emphasizing key regions of positive and negative charge localization. Among them, C1 and O8 atoms have the highest positive and negative charges respectively. Heat capacities at constant volume and at constant pressure, internal energy, enthalpy and entropy were observed to increase with rise in temperature contrasting with the trend observed for Gibbs free energy providing insights into the molecule's behavior under different temperature.</p> 2024-05-31T00:00:00+00:00 Copyright (c) 2024 Himalayan Physics https://nepjol.info/index.php/HP/article/view/57669 Height profile variations of ionospheric conductivity: A case study in Addis Ababa, Ethiopia 2023-08-15T13:19:56+00:00 Lake Endeshaw endeshawlake@gmail.com <p style="line-height: 150%;" align="justify">Ionospheric conductivity is the ability to conduct ionospheric current and is impacted by a variety of current system flows in height profiles, which increase ionosphere conductivity. In this study, we have analyzed the height profiles of the ionospheric conductivity daily and monthly variations in Addis Ababa, Ethiopia, during a very low solar activity phase in the year 2020. The daily height profile variations of ionospheric conductivity in Addis Ababa with geographic latitude 9<sup>o</sup> N and longitude 39<sup>o</sup> E are estimated at midnight (00:00 UT), morning (09:00 UT), mid-day (12:00 UT), and early nighttime (18:00 UT). The monthly variations of ionospheric conductivity (parallel, Pedersen, and Hall conductivity) are also presented for all months, with the highest ionospheric variability occurring after noon (14.00 UT). At midnight (00:00 UT) and early nighttime (18:00 UT), the ionospheric conductivity shows more fluctuation than in the morning (09:00 UT) and midday (12:00 UT) in diurnal variation. The monthly variations of ionospheric conductivity (parallel, Pedersen, and Hall conductivity) in the daytime at 14:00 UT increase steeply to reach their peak values and keep the sharpness of their variability.</p> 2024-06-06T00:00:00+00:00 Copyright (c) 2024 Himalayan Physics