Equipe de Chimie Physique, IPREM UMR5254, Université de Pau et des Pays de l'Adour , 64000 Pau, France.
Dipartimento di Chimica and NIS (Nanostructured Interfaces and Surfaces) Centre, Università di Torino , via Giuria 5, I-10125 Torino, Italy.
J Chem Theory Comput. 2016 Jan 12;12(1):107-13. doi: 10.1021/acs.jctc.5b00791. Epub 2015 Dec 18.
The electronic second harmonic generation (SHG) tensor, d, of crystalline urea and potassium dihydrogen phosphate (KDP) is evaluated as a function of frequency using a Gaussian type basis set and the Coupled Perturbed Hartree-Fock (CPHF) and Kohn-Sham (CPKS) schemes as implemented in the CRYSTAL code. The results of various functionals, including LDA, GGA (PBE), and global and range-separated hybrids (B3LYP, PBE0, LC-BLYP), as well as Hartree-Fock, are compared. It is found that the calculated SHG intensity always decreases as the percentage of exact exchange increases. The hybrid functionals turn out to provide results that agree well with experiment. For urea and KDP the percentage of exact exchange determined by the inverse dielectric constant is too large. At 1064 nm the vibrational contribution for urea is found to be less than 5% of the total value. To the authors' knowledge, this is the first coupled (self-consistent) calculation of SHG for any periodic system.
利用高斯型基组和 CRYSTAL 代码中实现的耦合微扰哈特ree-fock（CPHF）和 Kohn-Sham（CPKS）方案，评估了晶体尿素和磷酸二氢钾（KDP）的电子二次谐波（SHG）张量 d 随频率的变化。比较了各种泛函（包括 LDA、GGA（PBE）以及全局和范围分离的杂化（B3LYP、PBE0、LC-BLYP）以及哈特ree-fock）的结果。结果发现，随着交换精确程度的增加，计算出的 SHG 强度总是减小。杂化泛函提供的结果与实验结果吻合得很好。对于尿素和 KDP，由介电常数倒数确定的精确交换的百分比太大。在 1064nm 处，发现尿素的振动贡献小于总贡献的 5%。据作者所知，这是首次对任何周期性体系进行的耦合（自洽）SHG 计算。
