SALMON: Scalable Ab-initio Light-Matter simulator for Optics and Nanoscience

SALMON (Scalable Ab-initio Light-Matter simulator for Optics and Nanoscience, http://salmon-tddft.jp) is a software package for the simulation of electron dynamics and optical properties of molecules, nanostructures, and crystalline solids based on first-principles time-dependent density functional theory. The core part of the software is the real-time, real-space calculation of the electron dynamics induced in molecules and solids by an external electric field solving the time-dependent Kohn–Sham equation. Using a weak instantaneous perturbing field, linear response properties such as polarizabilities and photoabsorptions in isolated systems and dielectric functions in periodic systems are determined. Using an optical laser pulse, the ultrafast electronic response that may be highly nonlinear in the field strength is investigated in time domain. The propagation of the laser pulse in bulk solids and thin films can also be included in the simulation via coupling the electron dynamics in many microscopic unit cells using Maxwell’s equations describing the time evolution of the electromagnetic fields. The code is efficiently parallelized so that it may describe the electron dynamics in large systems including up to a few thousand atoms. The present paper provides an overview of the capabilities of the software package showing several sample calculations.

SALMON（Scalable Ab-initio Light-Matter simulator for Optics and Nanoscience，http://salmon-tddft.jp）是一款基于第一性原理时变密度泛函理论，用于模拟分子、纳米结构和晶体固体电子动力学及光学特性的软件包。该软件的核心部分是对由外部电场在分子和固体中诱导的电子动力学进行实时、空间实时计算，求解时变Kohn-Sham方程。通过使用微弱瞬时扰动场，可以确定孤立系统中的极化率和光吸收以及周期性系统中的介电函数等线性响应特性。利用光学激光脉冲，研究在时间域中可能因场强非线性而变得高度复杂的超快电子响应。通过将麦克斯韦方程耦合到多个微观单元细胞中的电子动力学，可以模拟激光脉冲在块状固体和薄膜中的传播。该代码经过高效并行化处理，能够描述包括数千个原子在内的大规模系统的电子动力学。本文概述了该软件包的功能，并展示了几个示例计算。