Pascale Fabien, Zicovich-Wilson Claudio M, Orlando Roberto, Roetti Carla, Ugliengo Piero, Dovesi Roberto
Laboratoire de Cristallographie et Modélisation des Matériaux Minéraux et Biologiques, Université Henri Poincaré, BP 239, 54506 Vandoeuvre les Nancy Cedex, France.
J Phys Chem B. 2005 Apr 7;109(13):6146-52. doi: 10.1021/jp050316z.
The vibrational spectrum of Mg(3)Al(2)Si(3)O(12) pyrope is calculated at the Gamma point by using the periodic ab initio CRYSTAL program that adopts an all-electron Gaussian-type basis set and the B3LYP Hamiltonian. The full set of frequencies (17 IR active, 25 RAMAN active, 55 silent modes) is calculated. The effect of the basis set and of the computational parameters on the calculated frequencies is discussed. It is shown that the mean absolute difference with respect to the experimental IR and RAMAN data is as small as 6 and 8 cm(-1), respectively. The IR and RAMAN modes are fully characterized by various tools such as isotopic substitution, direct inspection of the eigenvectors, and graphical representation. The present calculation permits to clarify some of the assignment and interpretation problems raised by experiment and previous simulations with force fields.
使用采用全电子高斯型基组和B3LYP哈密顿量的周期性从头算CRYSTAL程序，在Γ点计算了镁铝榴石Mg(3)Al(2)Si(3)O(12)的振动光谱。计算了完整的频率集（17个红外活性模式、25个拉曼活性模式、55个非活性模式）。讨论了基组和计算参数对计算频率的影响。结果表明，相对于实验红外和拉曼数据的平均绝对差值分别小至6和8 cm⁻¹。通过同位素取代、本征向量的直接检查和图形表示等各种工具对红外和拉曼模式进行了全面表征。目前的计算有助于澄清实验和先前力场模拟提出的一些归属和解释问题。
