期刊
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
卷 12, 期 45, 页码 14960-14966出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c0cp00411a
关键词
-
Car-Parrinello molecular dynamics (CPMD) are widely used to investigate the dynamical properties of molecular systems. An important issue in such applications is the dependence of dynamical quantities such as molecular vibrational frequencies upon the fictitious orbital mass mu. Although it is known that the correct Born-Oppenheimer dynamics are recovered at zero mu, it is not clear how these dynamical quantities are to be rigorously extracted from CPMD calculations. Our work addresses this issue for vibrational frequencies. We show that when the system is sufficiently close to the ground state the calculated ionic vibrational frequencies are omega(M) = omega(0M)[1 - C(mu/M)] for small mu/M, where omega(0M) is the Born-Oppenheimer ionic frequency, M the ionic mass, and C a constant that depends upon the ion-orbital coupling force constants. Our analysis also provides a quantitative understanding of the orbital oscillation amplitudes, leading to a relationship between the adiabaticity of a system and the ion-orbital coupling constants. In particular, we show that there is a significant systematic dependence of calculated vibrational frequencies upon how close the CPMD trajectory is to the Born-Oppenheimer surface. We verify our analytical results with numerical simulations for N-2, Sn-2, and H/Si(100)-(2x1).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据