Accelerating Density Fitting with Adaptive Precision and 8-Bit Integer on AI Accelerators

The emergence of artificial intelligence (AI) accelerators like NVIDIA Tensor Cores offers new opportunities to speed up tensor-heavy scientific computations. However, applying them to quantum chemistry is challenging due to strict accuracy demands and irregular data patterns. We propose an adaptive precision algorithm to accelerate the density fitting (DF) method with Gaussian basis sets on AI accelerators using 8-bit integer (INT8) arithmetics. Implemented in the GPU-accelerated PySCF package, the algorithm is tested on more than 20 molecular systems with different NVIDIA GPUs. Compared to the standard FP64 code, our algorithm is up to 204% faster on an RTX 4090 gaming GPU and up to 364% faster on an RTX 6000 Ada workstation GPU without compromising the converged energy. This work demonstrates a practical approach to using AI hardware for reliable quantum chemistry simulations.