## Scientific Computation and Applied & Industrial Mathematics: Bernie Shizgal

- Date: 03/06/2018

University of British Columbia

Pseudospectral Methods with Nonclassical Quadratures

A spectral method for the solution of integral and differential equations is generally understood to be an expansion of the solution in a Fourier series. Chebyshev polynomials are also often the preferred basis set for many problems. In kinetic theory, the Sonine polynomials have been used for decades for the solution of the Boltzmann equation and the calculation of transport coefficients. This talk will focus on the use of nonclassical polynomials orthonormal with respect to an appropriate weight function chosen dependent on the problem considered. The associated quadrature rules are also used in the pseudospectral solution of several different problems in kinetic theory and quantum mechanics. The recurrence coefficients in the three term recurrence relation for the nonclassical polynomials define the Jacobi matrix, J, and are determined numerically with the Gautschi-Stieltjes procedure. The quadrature points are the eigenvalues of J and the weights are the first components of the i th eigenfunction. This methodology is applied to the solution of the Fokker-Planck equation (1), the Schroedinger equation (2), the evaluation of integrals in quantum chemistry (3) and for nuclear reaction rate coefficients (4).

(1) Pseudospectral solution of the Fokker-Planck equation: the eigenvalue spectrum and the approach to equilibirum. J. Stat. Phys. 164, 1379-1393 (2016).

(2) Pseudospectral method of solution of the Schroedinger equation with nonclassical polynomials; the Morse and Poschl-Teller (SUSY) potentials. J. Comput. Theor. Chem. 1084, 51-58 (2016).

(3) A novel Rys quadrature algorithm for use in the calculation of electron repulsion integrals. J. Comput. Theor. Chem. 1074, 178-184 (2015).

(4) An efficient nonclassical quadrature for the calculation of nonresonant nuclear fusion reaction rate coefficients from cross section data. Comp. Phys. Comm. 205, 61-69 (2016).

Location: ESB 4133 (PIMS Lounge)