Dr. O. S. K. Subramanya Sastry

Scopus Publications

Genetic Algorithm Approach to Study Low-Energy Alpha–Deuteron Elastic Scattering using the Phase Function Method
Arushi Sharma, Ayushi Awasthi, Jyoti Sharma, Ishwar Kant, M R Ganesh Kumar, O S K S Sastri
Progress of Theoretical and Experimental Physics, 2026
The present study focuses on the analysis of elastic scattering in the $\\alpha \\!-\\!d$ system for low-energy data up to 14 $\\mathrm{MeV}$. This system holds particular significance due to its direct connection to the $^6\\mathrm{Li}$ production reaction, which is an important process in nuclear astrophysics and light nucleus synthesis. The primary objective of this investigation is to explore the low-lying excited states of positive parity with isospin $T=0$, which are crucial for accurately describing the resonance behavior and underlying nuclear dynamics of the system. The central idea of this paper is to obtain the interaction potential using the inverse scattering method: we employ the genetic algorithm approach. In this framework, the genetic algorithm is guided by the underlying physical laws, enabling accurate extraction of the inverse scattering potential from the elastic scattering data. In our methodology, as a reference potential, a combination of three smoothly joined Morse functions is utilized, characterized by 10 model parameters. These parameters are optimized in an iterative fashion to ensure the best fit to the phase shifts extracted from the experimental scattering data. The process of optimization is guided by the computed scattering phase shifts by solving the phase equation using the fifth-order Runge–Kutta method for the reference potential in each iteration. Our approach yields inverse potentials for both single- and multichannel scattering. Using the scattering phase shifts obtained from these inverse potentials, we calculate the partial cross section to determine the resonance energies and decay widths. The obtained values for the resonance energies and decay widths for the $^3D_1$, $^3D_2$, and $^3D_3$ states of $\\alpha \\!-\\!d$ are in correspondence with the experimental results.
A novel computational approach for study of proton–proton scattering
Arushi Sharma, Ayushi Awasthi, O. S. K. S. Sastri
Scientific Reports, 2025
In this paper, we have implemented a novel computational approach to study proton-proton scattering. The approach is applicable to all charged particle scattering scenarios and solves the challenge of incorporating the long-range Coulomb interaction alongside the short nuclear interaction using the phase function method. The key idea is to construct a reference potential using three smoothly joined Morse functions that collectively capture both nuclear and electromagnetic interactions. The reference potential is utilized in solving the phase equation which is derived by the transformation of the Schrodinger equation, for obtaining the scattering phase shifts for different values of orbital angular momentum called as $$\\ell$$ -channels (S, P, D, F, G, H). The parameters of reference potential are optimized to minimize the Mean Squared Error between obtained and expected phase shifts, resulting in the construction of inverse potential for various $$\\ell$$ -channels of the proton-proton system. Utilizing the phase shifts obtained from the inverse potentials, we have calculated the total cross-section and the low energy effective-range parameters, which have been found to be in excellent match with the experimental data.
Genetic-algorithm-based inverse potentials for resonant states of α- 12C using the variable phase approach
Ayushi Awasthi, Arushi Sharma, Barbie, Ishwar Kant, O. S. K. S. Sastri
Physical Review C, 2025
Elastic scattering between $\ensuremath{\alpha}$ particles and $^{12}\mathrm{C}$ nuclei plays a crucial role in understanding resonance phenomena in light nuclear systems. In this work, we construct inverse potentials for resonant states in $\ensuremath{\alpha}\text{\ensuremath{-}}^{12}\mathrm{C}$ elastic scattering using the variable phase approach, in tandem with a genetic-algorithm-based optimization technique. The reference function for the potential in the phase equation is chosen as a combination of three smoothly joined Morse-type functions. The parameters of the reference function are genetically evolved to minimize the the mean-squared error (MSE) between the numerically obtained scattering phase shifts and the expected values. To avoid overfitting and ensure model generalization, we employ a fivefold cross-validation strategy, where the genetic algorithm (GA) minimizes the average validation error across folds. The resulting inverse potentials accurately reproduce the resonance energies (${E}_{r}$) and the resonance widths (${\mathrm{\ensuremath{\Gamma}}}_{r}$) for the ${\ensuremath{\ell}}^{\ensuremath{\pi}}$ states, ${1}^{\ensuremath{-}}$, ${2}^{+}$, ${3}^{\ensuremath{-}}$, and ${4}^{+}$, showing excellent agreement with experimental data. This computational approach to constructing inverse potentials serves as a complement to conventional direct methods for investigating nuclear-scattering phenomena.
Genetic algorithm-based inverse optimization of interaction potential for nucleon-deuteron scattering below break-up threshold
Ayushi Awasthi, Arushi Sharma, Ishwar Kant, M.R. Ganesh Kumar, O.S.K.S. Sastri
Computer Physics Communications, 2025
Numerical Simulation Study of Neutron-Proton Scattering Using Phase Function Method: Part 2
Shikha Awasthi, Anil Khachi, Lalit Kumar, O. S. K. S. Sastri
Resonance, 2025
Numerical Simulation Study of Neutron-Proton Scattering Using Phase Function Method: Part 1
Shikha Awasthi, Anil Khachi, Lalit Kumar, O. S. K. S. Sastri
Resonance, 2025
Numerical Construction of Parametrized Potentials for Nucleon-Alpha Inverse Scattering Using Variational Monte Carlo and Phase Function Method
Lalit Kumar, Anil Khachi, O. S. K. S. Sastri
Computational Mathematics and Mathematical Physics, 2025
Neutron and proton scattering with stable alpha particles can be represented as a two-particle system. In this work, we present a numerical algorithm developed to obtain parametric potentials of the inverse scattering problem by solving the Riccati-type non-linear differential equation, known as the phase equation, alongside the Variational Monte Carlo method. Local interaction potentials for the resonant $${{p}_{{1/2}}}$$ and $${{p}_{{3/2}}}$$ channels are constructed using the Morse potential, derived from scattering phase shift (SPS) data for neutron-alpha and proton-alpha scattering. The non-local interaction potential in the $$p\alpha $$ system is modeled using a screened Coulomb potential. The phase equation for the $${{p}_{{1/2}}}$$ and $${{p}_{{3/2}}}$$ channels is solved numerically using the fifth-order Runge–Kutta method. The parameters of the Morse function are optimized by minimizing the mean absolute percentage error (MAPE) between the calculated and experimental phase shifts, through an iterative process involving Monte Carlo sampling and variational techniques. This ensures the accurate reproduction of experimental SPS data. Resonance energies, obtained (experimental) from partial cross-section plots for the $${{p}_{{1/2}}}$$ and $${{p}_{{3/2}}}$$ states in the $$n\alpha $$ system, are 4.10 (4 ± 1) MeV and 0.93 (0.89) MeV, respectively, while for the $$p\alpha $$ system, they are 5.31 (5 ± 2) MeV and 1.97 (1.96) MeV. The total cross-section for the $$n\alpha $$ system is in agreement with values found in the literature. This study demonstrates the effectiveness of the proposed numerical algorithm for constructing parametric potentials and shows its ability to accurately reproduce phase shifts and cross-sections in line with experimental data.
Constructing inverse potentials for resonant states of α-3H and α-3He scattering directly from phase shifts
Ishwar Kant, Ayushi Awasthi, Arushi Sharma, Shikha Awasthi, OSKS Sastri, MR Ganesh Kumar
Physica Scripta, 2025
In this paper, the inverse potentials for the resonant f states of α-3H and α-3He are constructed using the phase function method by utilizing an reference potential approach. Central Idea: A combination of three Morse functions are chosen over three regions of interaction and are joined smoothly at the intervening boundaries to prepare the reference potential. While the regular Morse function captures the nuclear and Coulomb interactions at short and medium ranges, an inverse Morse function is chosen to obtain the Coulomb barrier that arises because of the long-range Coulomb interaction. This reference potential is representative of a large family of curves consisting of eight distinct model parameters and two intermediate points. Methodology: The phase equation is solved using the Runge-Kutta 5th order method for the input reference potential to obtain the scattering phase shifts at various center of mass energies. The model parameters are then adjusted using the genetic algorithm in an iterative fashion to minimize the mean square error between the simulated and expected phase shift values. Results: Our approach successfully constructed the inverse potentials for the resonant f states of the α-3H and α-3He systems, achieving convergence with a minimized mean square error. The resonance energies and widths for the α-3H system for the f 5 / 2 − and f 7 / 2 − states are determined to be [4.19 (4.14), 1.225 (0.918)] MeV and [2.20 (2.18), 0.099 (0.069)] MeV, respectively. For the f 5 / 2 − and f 7 / 2 − states of the α-3He system, the resonance energies and widths are [5.03 (5.14), 1.6 (1.2)] MeV and [2.99 (2.98), 0.182 (0.175)] MeV, respectively. Conclusion: Our fitting procedure of the available experimental data utilizing a combination of smoothly joined Morse functions effectively captures both short-range nuclear and long-range Coulomb interactions, providing an accurate model for nuclear scattering involving charged particles.
Elastic scattering study of α- 3H and α- 3He modeled by Malfliet–Tjon potential using phase function method
Shikha Awasthi, Ishwar Kant, Anil Khachi, O. S. K. S. Sastri
Indian Journal of Physics, 2025
Variational Monte Carlo optimization of proton-proton scattering potential using the phase function method
SHIKHA AWASTHI, ANIL KHACHI, O.S.K.S. SASTRI
Turkish Journal of Physics, 2025
The Riccati-type nonlinear differential equation, also known as the Phase Function equation, is used to construct local inverse potentials for the 1S0 - pp state by bypassing the well-known Schrödinger equation. The pp interaction is described using the Malfliet-Tjon potential model for the nuclear component combined with a screened Coulomb potential, with the phase equation solved via the fourth-order Runge-Kutta (RK-4) method. Based on our analysis, we confirm that the optimized interaction potential closely matches the well-known realistic Argonne V18 and Reid potentials for the 1S0 state, and the computed phase shifts and cross-sections show excellent agreement with experimental data. This study demonstrates the efficacy of PFM in accurately modeling nuclear interactions, contributing to the refinement of theoretical frameworks for high-energy scattering phenomena.
Variational optimization for constructing inverse potentials of proton-proton scattering: a phase function method study
Lalit Kumar, Arushi Sharma, Anil Khachi, Ayushi Awasthi, O. S. K. S. Sastri
Indian Journal of Physics, 2025
Isospin-Dependent Inverse Potentials for Elastic Pion Nucleon Scattering in the S11 and S31 Channels
Ayushi Awasthi, Sanyam Walia, Arushi Sharma, Ishwar Kant, O. S. K. S. Sastri
Springer Proceedings in Physics, 2025
Optical Inverse Potentials for Proton-Proton Scattering up to 1GeV
Arushi Sharma, Gargi Rathore, Ayushi Awasthi, Ishwar Kant, O. S. K. S Sastri
Springer Proceedings in Physics, 2025
Energy-Dependent Inverse Potentials for Neutron-Proton Elastic Scattering up to 1050 MeV Using Piecewise Morse Functions
Ayushi Awasthi, Tanisha Thakur, Arushi Sharma, Ishwar Kant, O. S. K. S. Sastri
Springer Proceedings in Physics, 2025
Simulation Study of Arbitrary 1D Periodic Potentials by Modified Marsiglio’s Matrix Approach using Gnumeric Spreadsheet
Aditi Sharma, Arushi Sharma, O. S. K. S. Sastri
Resonance, 2024
High-precision inverse potentials for neutron-proton scattering using piece-wise smooth Morse functions
Ayushi Awasthi, Arushi Sharma, Ishwar Kant, O. S. K. S. Sastri
Chinese Physics C, 2024
Algorithm to Obtain Inverse Potentials for α–α Scattering Using Variable Phase Approach
Anil Khachi, Shikha Awasthi, Lalit Kumar, O. S. K. S. Sastri
Computational Mathematics and Mathematical Physics, 2024
Real and Imaginary Phase Shifts for Nucleon–Deuteron Scattering Using Phase Function Method
Shikha Awasthi, O. S. K. S. Sastri
Physics of Atomic Nuclei, 2024
Constructing inverse scattering potentials for charged particles using a reference potential approach
O. S. K. S. Sastri, Arushi Sharma, Ayushi Awasthi
Physical Review C, 2024
Comparative study of α - α interaction potentials constructed using various phenomenological models
AYUSHI AWASTHI, O S K S SASTRI
Turkish Journal of Physics, 2024
Cross Section for 3H(α,γ)7Li Astrophysical Reaction Using Scattering Phase Shifts
Shikha Awasthi, Anil Khachi, O. S. K. S. Sastri
Springer Proceedings in Physics, 2024
Inverse potentials for all ℓ channels of neutron-proton scattering using reference potential approach
Anil Khachi, Lalit Kumar, Ayushi Awasthi, O S K S Sastri
Physica Scripta, 2023
Deuteron structure and form factors: Using an inverse potential approach
Anil Khachi, Lalit Kumar, M. R. Ganesh Kumar, O. S. K. S. Sastri
Physical Review C, 2023
Alpha–Alpha Scattering Potentials for Various l-Channels Using Phase Function Method
Anil Khachi, Lalit Kumar, O. S. K. S. Sastri
Physics of Atomic Nuclei, 2022
Optimization of semi-empirical mass formula co-efficients using least square minimization and variational Monte-Carlo approaches
Swapna Gora, O S K S Sastri, S K Soni
European Journal of Physics, 2022
An Innovative Approach to Construct Inverse Potentials Using Variational Monte-Carlo and Phase Function Method: Application to np and pp Scattering
O.S.K.S Sastri, Anil Khachi, Lalit Kumar
Brazilian Journal of Physics, 2022
Numerical simulation of ro-vibrational spectra for diatomic molecules using the Numerov matrix method
Aditi Sharma, O S K S Sastri
European Journal of Physics, 2022
Numerical solution of Schrodinger equation for rotating Morse potential using matrix methods with Fourier sine basis and optimization using variational Monte-Carlo approach
Aditi Sharma, Oruganti S. K. S. Sastri
International Journal of Quantum Chemistry, 2021
Numerical simulation of quantum anharmonic oscillator, embedded within an infinite square well potential, by matrix methods using Gnumeric spreadsheet
Aditi Sharma, O S K S Sastri
European Journal of Physics, 2020
Simulation study of nuclear shell model using sine basis
Aditi Sharma, Swapna Gora, Jithin Bhagavathi, O. S. K. S Sastri
American Journal of Physics, 2020
Novel coincidence setup using indigenously developed portable USB gamma spectrometer and associated analysis software
Jithin B.P., O.S.K.S. Sastri
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment, 2020
Gate field controlled and temperature dependent quantum transport in (10,0) carbon nanotube field effect transistor
Tapender Singh, O. S. K. S. Sastri, Padmnabh Rai
Aip Advances, 2018
Effect of listening to Vedic chants and Indian classical instrumental music on patients undergoing upper gastrointestinal endoscopy: A randomized control trial
Neetu Sharma, Anita Padam, O. S. K. S Sastri, Shivani Mahajan, Rajesh Sharma, Deepak Sharma
Indian Journal of Psychiatry, 2017
Effect of doping on electronic properties of HgSe
Abhinav Nag, O. S. K. S. Sastri, Jagdish Kumar
Aip Conference Proceedings, 2016
A computer simulation using spreadsheets for learning concept of steady-state equilibrium
Vandana Sharda, O S K S Sastri, Jyoti Bhardwaj, Arbind K Jha
Physics Education, 2016
Effect of mechanical strain on electronic properties of bulk MoS2
Sandeep Kumar, Jagdish Kumar, O. S. K. S. Sastri
Aip Conference Proceedings, 2015
Effect of strain along C-axis NbS2
Tapender Singh, Jagdish Kumar, O. S. K. S. Sastri
Aip Conference Proceedings, 2015
Electronic properties of graphene and effect of doping on the same
Abhinav Nag, Jagdish Kumar, O. S. K. S. Sastri
Aip Conference Proceedings, 2015
Design of instructional objectives of undergraduate solid state physics course: A first step to physics education research
S. Sharma, O. Sastri, P. K. Ahluwalia, Boonchoat Paosawatyanyong, Pornrat Wattanakasiwich
Aip Conference Proceedings, 2010
K-forbidden allowed β transitions in heavy nuclei
P. C. Sood, O. S. K. S. Sastri, R. K. Jain
European Physical Journal A, 2009
Relative longevity of odd-N nuclei in the heavy actinide region
P C Sood, O S K S Sastri, Raj Kumar Jain
Journal of Physics G Nuclear and Particle Physics, 2008
Intrinsically forbidden 'allowed' beta transitions in actinides
O S K S Sastri, Raj Kumar Jain, P C Sood
Journal of Physics G Nuclear and Particle Physics, 2006
Structure of long-lived nuclear species of Einsteinium
National Academy Science Letters, 2006
Unusual features of β transition rates in heavy deformed nuclei
P. C. Sood, Raj Kumar Jain, O. S. K. S. Sastri
Physical Review C Nuclear Physics, 2004
Identification of a four-particle state in the N = 152 nucleus 250Cf
P C Sood, Raj Kumar Jain, O S K S Sastri
Journal of Physics G Nuclear and Particle Physics, 2003

Dr. O. S. K. Subramanya Sastry

RESEARCH INTERESTS

Scopus Publications