TAILIEUCHUNG - Ideas of Quantum Chemistry P83

Ideas of Quantum Chemistry P83 shows how quantum mechanics is applied to chemistry to give it a theoretical foundation. The structure of the book (a TREE-form) emphasizes the logical relationships between various topics, facts and methods. It shows the reader which parts of the text are needed for understanding specific aspects of the subject matter. Interspersed throughout the text are short biographies of key scientists and their contributions to the development of the field. | 786 14. Intermolecular Motion of Electrons and Nuclei Chemical Reactions the molecule undergoes when oscillating perpendicularly29 to xIRC s . Simply the valley bottom profile results from the fact that the molecule hardly holds together when moving along the reaction coordinate s a chemical bond breaks while other bonds remain strong and it is not so easy to stretch their strings. This suggests that there is slow motion along s and fast oscillatory motion along the coordinates Qk. Since we are mostly interested in the slow motion along s we may average over the fast motion. The philosophy behind the idea is that while the system moves slowly along s it undergoes a large number of oscillations along Qk. After such vibrational averaging the only information that remains about the oscillations are the vibrational quantum levels for each of the oscillators the levels will depend on s . VIBRATIONALLY ADIABATIC APPROXIMATION The fast vibrational motions will be treated quantum mechanically and their total energy will enter the potential energy for the classical motion along s. This approximation parallels the adiabatic approximation made in Chapter 6 where the fast motion of electrons was separated from the slow motion of the nuclei. There the total electronic energy became the potential energy for the motion of nuclei here the total vibrational energy the energy of the corresponding harmonic oscillators in their quantum states becomes the potential energy for the slow motion along s. This concept is called the vibrationally adiabatic approximation. In this approximation to determine the stage of the reaction we give two classical quantities where the system is on the reaction path s and how fast the system moves along the reaction path ps . Also we need the quantum states of the oscillators vibrating perpendicularly to the reaction path vibrational quantum number vk 0 1 2 . for each of the oscillators . Therefore the potential energy for the slow motion along the .

TỪ KHÓA LIÊN QUAN
TAILIEUCHUNG - Chia sẻ tài liệu không giới hạn
Địa chỉ : 444 Hoang Hoa Tham, Hanoi, Viet Nam
Website : tailieuchung.com
Email : tailieuchung20@gmail.com
Tailieuchung.com là thư viện tài liệu trực tuyến, nơi chia sẽ trao đổi hàng triệu tài liệu như luận văn đồ án, sách, giáo trình, đề thi.
Chúng tôi không chịu trách nhiệm liên quan đến các vấn đề bản quyền nội dung tài liệu được thành viên tự nguyện đăng tải lên, nếu phát hiện thấy tài liệu xấu hoặc tài liệu có bản quyền xin hãy email cho chúng tôi.
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.