Results 41 to 50 of about 16,801 (158)

Piecewise Linearity of Approximate Density Functionals Revisited: Implications for Frontier Orbital Energies

, 2013
In the exact Kohn-Sham density-functional theory (DFT), the total energy versus the number of electrons is a series of linear segments between integer points.
Kraisler, Eli, Kronik, Leeor
core   +1 more source

Piecewise fractional derivatives and wavelets in epidemic modeling

Alexandria Engineering Journal
In this paper, we propose a novel methodology for studying the dynamics of epidemic spread, focusing on the utilization of fundamental mathematical concepts related to piecewise differential and integral operators. These mathematical tools play a crucial role in the process of modeling epidemic phenomena, enabling us to investigate the behavior of ...
Mutaz Mohammad, Mohyeedden Sweidan, Alexander Trounev   +2 more
openaire   +2 more sources

Koopmans-compliant functionals and their performance against reference molecular data

, 2014
Koopmans-compliant functionals emerge naturally from extending the constraint of piecewise linearity of the total energy as a function of the number of electrons to each fractional orbital occupation. When applied to approximate density-functional theory,
Borghi, Giovanni, Dabo, Ismaila, Ferretti, Andrea, Marzari, Nicola, Nguyen, Ngoc Linh   +4 more
core   +1 more source

Fractional Stochastic Van der Pol Oscillator with Piecewise Derivatives

Journal of Mathematics
This work investigates piecewise Vand der Pol oscillator under the arbitrary order, piecewise derivatives, and power nonlinearities to present a novel idea of piecewise systems using the classical‐power‐law randomness and classical Mittag–Leffler‐law‐randomness.
Atul Kumar, Khursheed Alam, Mati ur Rahman, Homan Emadifar, Geeta Arora, Ahmed A. Hamoud   +5 more
openaire   +2 more sources

A numerical approach for a category of piecewise fractional variational problems depending on an indefinite integral

Alexandria Engineering Journal
The primary focus of this study is to introduce some kinds of piecewise fractional derivatives (PFDs). These derivatives are defined using fractional derivatives in both the Atangana–Baleanu and Caputo senses.
M.H. Heydari, D. Baleanu
doaj   +1 more source

The Evolution of COVID-19 Transmission with Superspreaders Class under Classical and Caputo Piecewise Operators: Real Data Perspective from India, France, and Italy

Fractal and Fractional, 2023
In this study, we analyze the transmission of the COVID-19 model by using a piecewise operator in the classical Caputo sense. The existence along with the uniqueness of the solution of the COVID-19 model under a piecewise derivative is presented.
Shabir Ahmad, Salma Haque, Khalid Ali Khan, Nabil Mlaiki   +3 more
doaj   +1 more source

Crossover Dynamics of Rotavirus Disease under Fractional Piecewise Derivative with Vaccination Effects: Simulations with Real Data from Thailand, West Africa, and the US

Symmetry, 2022
Many diseases are caused by viruses of different symmetrical shapes. Rotavirus particles are approximately 75 nm in diameter. They have icosahedral symmetry and particles that possess two concentric protein shells, or capsids. In this research, using a piecewise derivative framework with singular and non-singular kernels, we investigate the evolution ...
Surapol Naowarat, Shabir Ahmad, Sayed Saifullah, Manuel De la Sen, Ali Akgül   +4 more
openaire   +3 more sources

Fractional Calculus of Piecewise Continuous Functions

Fractal and Fractional
The fractional derivative computation of piecewise continuous functions is treated with generality. It is shown why some applications give incorrect results and why Caputo derivative give strange results. Some examples are described.
Manuel Duarte Ortigueira
doaj   +1 more source

New crossover lumpy skin disease: Numerical treatments

Partial Differential Equations in Applied Mathematics
This work expands on a novel piecewise mathematical model of Lumpy Skin Disease (LSD) in three time intervals by utilizing fractional stochastic derivatives and variable-order differential equations.
NH Sweilam, Waleed Abdel Kareem, SM Al-Mekhlafi, Muner M Abou Hasan, Taha H El-Ghareeb, TM Soliman   +5 more
doaj   +1 more source

Stationarity-conservation laws for certain linear fractional differential equations

, 2001
The Leibniz rule for fractional Riemann-Liouville derivative is studied in algebra of functions defined by Laplace convolution. This algebra and the derived Leibniz rule are used in construction of explicit form of stationary-conserved currents for ...
Douglas J F, Hilfer R, Hilfer R, Hilfer R, Klimek M, Malgorzata Klimek, Miller K S, Nigmatullin R R, Oldham K B, Osler T J, Osler T J, Osler T J, Podlubny I, Samko S G, Schiessel H, Takahashi Y, Zavada P   +16 more
core   +2 more sources