A GPGPU based program to solve the TDSE in intense laser fields through the finite difference approach

We present a General-purpose computing on graphics processing units (GPGPU) based computational program and framework for the electronic dynamics of atomic systems under intense laser fields. We present our results using the case of hydrogen, however the code is trivially extensible to tackle problems within the single-active electron (SAE) approximation. Building on our previous work, we introduce the first available GPGPU based implementation of the Taylor, Runge Kutta and Lanczos based methods created with strong field ab-initio simulations specifically in mind; CLTDSE. The code makes use of finite difference methods and the OpenCL framework for GPU acceleration. The specific example system used is the classic test system; Hydrogen. After introducing the standard theory, and specific quantities which are calculated, the code, including installation and usage, is discussed in-depth. This is followed by some examples and a short benchmark between an 8 hardware thread (i.e. logical core) Intel Xeon CPU and an AMD 6970 GPU, where the parallel algorithm runs 10 times faster on the GPU than the CPU. Program summary Program title: CLTDSE Catalogue identifier: AESM_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AESM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU General Public License, version 3 and above No. of lines in distributed program, including test data, etc.: 15 988 No. of bytes in distributed program, including test data, etc.: 233 518 Distribution format: tar.gz Programming language: C99 and OpenCL C. C99 conformance is ensured through use of C99 and pedantic flags under GCC and Clang. Computer: Single compute node. Operating system: GNU/Linux. It should, in principle, work with little modification for other Unix-Like systems. Has the code been vectorised or parallelised?: OpenCL is a parallel language. Thus CLTDSE can use all cores on a processor or GPU. OpenCL supports using all available compute units (GPUs and CPUs etc.), although this is not currently implemented in CLTDSE. RAM: Negligible RAM and GPU global memory (20MiB) Classification: 2.5. External routines: An OpenCL library; the current major packages are APP by AMD (CPU and AMD GPU), the NVIDIA driver (GPU), and the Intel SDK for OpenCL Applications (CPU and Intel HD Graphics). libconfig Nature of problem: Describing the dynamics of electrons under intense laser fields in atoms or molecules. Solution method: Solving the discretised system through finite difference using the Lanczos, Runge Kutta, and Taylor methods. Restrictions: The example problem which is implemented is under the single active electron approximation. Unusual features: Focused on GPGPU acceleration through OpenCL. Running time: The running time depends on the nature of the pulse. This can vary from seconds to tens of minutes. (C) 2014 Elsevier B.V. All rights reserved.