Tiresia: A code for molecular electronic continuum states and photoionization

The Tiresia program [1] provides access to numerically accurate solutions of the one-particle Schrödinger equation for highly excited states of complex polyatomic molecules, both bound and continuum, that cannot be described by conventional Quantum Chemistry approaches. It is based on an expansion of the required solution in a local multicentric basis set, with primitive functions built as products of a radial B-spline times a real spherical harmonic. In conjunction with Density Functional Theory (DFT), it has been extensively employed in a large variety of photoionization studies, also for rather large systems. Highly excited bound states as well as wavepacket propagation can also be accurately described. In fact, the flexibility of the basis essentially allows accurate solutions of linear operator equations, like Poisson or inhomogeneous perturbative equations, which are employed in the code. The program is parallelized with standard MPI-I instructions and makes extensive use of the Scalapack linear algebra library. Ancillary programs are available for the evaluation of photoionization cross sections and angular distributions from randomly to fully oriented molecules.

蒂雷西亚（Tiresia）程序[1]可提供复杂多原子分子高激发态（包括束缚态与连续态）的单粒子薛定谔方程数值精确解，这类体系无法通过传统量子化学方法进行描述。该程序基于将所需解在局域多中心基组下展开的方法，其基原函数由径向B样条（radial B-spline）与实球谐函数（real spherical harmonic）的乘积构建而成。结合密度泛函理论（Density Functional Theory, DFT）后，该程序已被广泛应用于各类光致电离研究，甚至可处理规模较大的分子体系。该程序还可精确描述高激发束缚态以及波包（wavepacket）的传播过程。实际上，该基组的灵活性使得程序可精确求解各类线性算子方程，例如代码中所采用的泊松方程与非齐次微扰方程。该程序采用标准MPI-I指令实现并行计算，并广泛使用Scalapack线性代数库。此外还配套有辅助程序，可用于计算从随机取向至完全取向分子的光致电离截面与角分布。