HSTERM — A program to calculate potential curves and radial matrix elements for two-electron systems within the hyperspherical adiabatic approach

• Published in: Computer physics communications Vol. 90; no. 2; pp. 311 - 339
• Main Authors: Abrashkevich, A.G., Abrashkevich, D.G., Shapiro, M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1995; Elsevier Science
• Subjects: Atomic physics; Computational techniques; Diabatic-by-sector approach; Dipole transition amplitudes; Eigensolutions; Exact sciences and technology; Finite element method; High-order accuracy approximations; Hyperspherical adiabatic representation; Hyperspherical coordinates; Mathematical methods in physics; Ordinary differential equations; Physics; Potential curves; Schrödinger equation; Two-electron systems; Atomic physics; Finite element method; Two-electron systems; Dipole transition amplitudes; High-order accuracy approximations; Ordinary differential equations; Hyperspherical coordinates; Hyperspherical adiabatic representation; Eigensolutions; Diabatic-by-sector approach; Schrödinger equation; Potential curves; Potential energy curve; Two electron system; Adiabatic approximation; Computer program; Differential equations; Schroedinger equation; Numerical method; Matrix elements
• ISSN: 0010-4655; 1879-2944
• DOI: 10.1016/0010-4655(95)00084-S

A FORTRAN 77 program is presented which calculates potential curves and matrix elements of radial coupling for two-electron systems using the hyperspherical coordinate method. The adiabatic and diabatic-by-sector close-coupling approaches are considered. The program calculates also the overlap matrices on borders of all sectors which are necessary for integration of close-coupling hyperradial equations within the sector-diabatic approach. It performs also the computation of the angular part of dipole amplitudes (in the length and acceleration forms) for dipole transitions between two given atomic states. The convergence and accuracy of the computational scheme elaborated are studied in details. Radial matrix elements computed by the HSTERM program can be used for the solution of the bound state and scattering problems for two-electron systems in both the adiabatic and diabatic-by-sector close-coupling approaches.