Del Vitto Annalisa, Giordano Livia, Pacchioni Gianfranco, Heiz Ulrich
Dipartimento di Scienza dei Materiali, Università Milano-Bicocca, via R. Cozzi 53, I-20125 Milano, Italy.
J Phys Chem B. 2005 Mar 3;109(8):3416-22. doi: 10.1021/jp044982w.
The bonding and vibrational properties of Pd(CO) and Pd(CO)(2) complexes formed at the (100) surface of MgO have been investigated using the gradient-corrected DFT approach and have been compared to the results of infrared and thermal desorption experiments performed on ultrathin MgO films. Two complementary approaches have been used for the calculation of the electronic properties: the embedded cluster method using localized atomic orbital basis sets and supercell periodic calculations using plane waves. The results show that the two methods provide very similar answers, provided that sufficiently large supercells are used. Various regular and defect adsorption sites for the Pd(CO) and Pd(CO)(2) have been considered: terraces, steps, neutral and charged oxygen vacancies (F and F(+) centers), and divacancies. From the comparison of the computed and experimental results, it is concluded that the most likely site where the Pd atoms are stabilized and where carbonyl complexes are formed are the F(+) centers, paramagnetic defects consisting of a single electron trapped in an anion vacancy.
利用梯度校正密度泛函理论（DFT）方法研究了在MgO（100）表面形成的Pd(CO)和Pd(CO)₂配合物的键合和振动特性，并将其与在超薄MgO薄膜上进行的红外和热脱附实验结果进行了比较。计算电子性质时使用了两种互补方法：使用局域原子轨道基组的嵌入团簇方法和使用平面波的超晶胞周期计算方法。结果表明，只要使用足够大的超晶胞，这两种方法能给出非常相似的结果。考虑了Pd(CO)和Pd(CO)₂的各种规则和缺陷吸附位点：平台、台阶、中性和带电氧空位（F和F⁺中心）以及双空位。通过比较计算结果和实验结果得出结论，Pd原子稳定且形成羰基配合物的最可能位点是F⁺中心，即单个电子被困在阴离子空位中的顺磁缺陷。
