Development of ab initio molecular orbital program for large-scale molecular systems

本研究项目的目的是开发一个从头算分子轨道程序，该程序可以高精度、高性能地确定包括1000多个原子在内的大型系统的电子结构。要实现这一目标，需要纯理论和实践两个方面：在理论上发展新方法，在算法和程序上发展新技术。在前者方面，我们的重点是发展(1)新的从头算分子轨道理论，特别是基于多参考的方法；(2)包含相对论效应的分子轨道理论；(3)密度泛函理论中的交换和相关泛函；成功开发了具有定域轨道的MRMP、具有CASCI参考的MRMP、准完全活动空间SCF方法、QCAS-SCF参考QDPT、RESC、三阶douglass - kroll方法、Dirac-Hatree-Fock和Dirac-Kohn-Sham方法的高效格式、相对论模型势、无参数交换泛函、单参数递进相关泛函。在后者方面，我们开发了基于高性能积分方法的分子积分程序Spherica，以及基于上述方案的Dirac-Hatree-Fock和Dirac-Kohn-Sham方法程序。这些程序不是简单地根据传统的计算技术编码的，而是通过使用包括分子积分在内的每个计算方案优化后发现的新技术获得的程序。

The aim of this research project is to develop an ab initio molecular orbital program that can determine the electronic structure of large-scale systems, including more than 1000 atoms, with high accuracy and high performance. To achieve this aim, both pure theoretical and practical aspects are necessary : development of new methods in theory and new technology in algorithm and program. In the former aspect, our focus was particularly on the development of (1) new ab initio molecular orbital theory, especially multireference-based methods, (2) molecular orbital theory including relativistic effects, and (3) exchange and correlation functional in density functional theory ; and we succeeded in the development of MRMP with localized orbitals, MRMP with CASCI reference, quasi-complete active space SCF method, QCAS-SCF reference QDPT, RESC, third-order Douglas-Kroll method, highly efficient scheme of Dirac-Hatree-Fock and Dirac-Kohn-Sham methods, relativistic model potentials, parameter-free exchange functional, one-parameter-progressive correlation functional. In the latter aspect, we developed a molecular integral program, Spherica, based on high-performance integral method, and the programs of Dirac-Hatree-Fock and Dirac-Kohn-Sham methods based on the above-mentioned schemes. These are not programs simply coded according to conventional computational techniques, but programs obtained by the use of new technologies found after optimization of every computational scheme including molecular integrals.