MCEND: An open-source program for quantum electron-nuclear dynamics

The software MCEND (Multi-Configuration Electron-Nuclear Dynamics) is a free open-source program package which simulates the quantum dynamics of electron-nuclei simultaneously for diatomic molecules. Its formulation, implementation, and usage are described in detail. MCEND uses a grid-based basis representation for the nuclei, and the electronic basis is derived from standard electronic structure basis sets on the nuclear grid. The wave function is represented as a sum over products of electronic and nuclear wave functions, thus capturing correlation effects between electrons, nuclei, and electrons and nuclei. The LiH molecule was used as an example for simulating the molecular properties such as the dipole moment and absorption spectrum.

软件MCEND（多配置电子-核动态）是一款免费开源的程序包，能够模拟双原子分子中电子与核的量子动力学。其公式推导、实现以及应用均被详细阐述。MCEND采用基于网格的基函数表示核，而电子基函数则源自于标准电子结构基函数在核网格上的推导。波函数以电子波函数和核波函数乘积之和的形式表示，从而捕捉电子与电子、核与电子之间的关联效应。以LiH分子为例，模拟了分子的性质，如偶极矩和吸收光谱等。