VeloxChem: GPU-accelerated Fock matrix construction enabling complex polarization propagator simulations of circular dichroism spectra of G-quadruplexes

An automatic code generated C++/HIP/CUDA implementation of the (auxiliary) Fock, or Kohn–Sham, matrix construction for execution in GPU-accelerated hardware environments is presented. The module is developed as part the quantum chemistry software package VeloxChem, employing localized Gaussian atomic orbitals. The per- formance and scaling characteristics are analyzed in view of the specific requirements for self-consistent field optimizations and response theory calculations. As an example, the electronic circular dichroism spectrum of a G-quadruplex is calculated at the level of time-dependent density functional theory in conjunction with the range-separated CAM-B3LYP exchange–correlation functional. Computational issues due to the high- density of states following the adoption of large-scale model systems is here bypassed with use of the complex polarization propagator approach. The origin of the negative Cotton effect in the long-wavelength onset of the experimental spectrum is elucidated in the large-scale modeling and shown to be associated with the TTA nucleobase linkers in the G-quadruplex.