Dipartimento di Chimica IFM, Università di Torino and Nanostructured Interfaces and Surfaces (NIS) Centre of Excellence, Via P. Giuria 7, 10125 Torino, Italy.
J Chem Phys. 2009 Nov 28;131(20):204509. doi: 10.1063/1.3267048.
The high-frequency dielectric varepsilon and the first nonlinear electric susceptibility chi((2)) tensors of crystalline potassium dihydrogen phosphate (KH(2)PO(4)) are calculated by using the coupled perturbed Hartree-Fock and Kohn-Sham methods as implemented in the CRYSTAL code. The effect of basis sets of increasing size on varepsilon and chi((2)) is explored. Five different levels of theory, namely, local-density approximation, generalized gradient approximation (PBE), hybrids (B3LYP and PBE0), and HF are compared using the experimental and theoretical structures corresponding not only to the tetragonal geometry I4d2 at room temperature but also to the orthorhombic phase Fdd2 at low temperature. Comparison between the two phases and their optical behavior is made. The calculated results for the tetragonal phase are in good agreement with the experimental data.
利用 CRYSTAL 代码中实现的耦合微扰哈特ree-fock 和 Kohn-Sham 方法，计算了晶体磷酸二氢钾（KH2PO4）的高频介电常数 varepsilon 和一阶非线性电感应系数 chi((2))张量。研究了基组大小对 varepsilon 和 chi((2))的影响。比较了五种不同的理论水平，即局域密度近似、广义梯度近似（PBE）、混合（B3LYP 和 PBE0）和 HF，使用不仅对应于室温下的四方相 I4d2，而且对应于低温下的正交相 Fdd2 的实验和理论结构。比较了两相及其光学性质。四方相的计算结果与实验数据吻合较好。
