Ⅰ. INTRODUCTIONIsotopic frequency shifts of vibrational frequencies of polyatomic molecules bring much benefit to the determination of force field constants. There are a variety of isotopic substitution rules for mol...Ⅰ. INTRODUCTIONIsotopic frequency shifts of vibrational frequencies of polyatomic molecules bring much benefit to the determination of force field constants. There are a variety of isotopic substitution rules for molecular vibrational fundamental frequencies, all of which are based on the GF matrix method, that is, with small vibrational amplitude approximation. For X-H(X=C, N, O, S, etc.) stretching vibrations with large anharmonicity, we discover at least展开更多
A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empi...A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empirical linear relationships that have been proposed for heterocyclics, alkanes and fluorinated benzenes. On the other hand, a unified relationship between the X-H bond angles and the experimental quantities (ω(?) and the coupling strength λ) is also presented for XH2, XH, and XH4 molecules or molecular fragments. Calculations of X-H bond angles for a number of molecules show that the results from our equations are in excellent agreement with the experimental values. Also we can extract the information of relative magnitude of bond coupling force field.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Ⅰ. INTRODUCTIONIsotopic frequency shifts of vibrational frequencies of polyatomic molecules bring much benefit to the determination of force field constants. There are a variety of isotopic substitution rules for molecular vibrational fundamental frequencies, all of which are based on the GF matrix method, that is, with small vibrational amplitude approximation. For X-H(X=C, N, O, S, etc.) stretching vibrations with large anharmonicity, we discover at least
基金Project supported by the National Natural Science Foundation of China
文摘A relationship between the X-H (X = N, O, C, and so on) equilibrium bond length in a Morse oscillator and the X-H stretching overtone frequency shifts is obtained theoretically. We use the equation to discuss the empirical linear relationships that have been proposed for heterocyclics, alkanes and fluorinated benzenes. On the other hand, a unified relationship between the X-H bond angles and the experimental quantities (ω(?) and the coupling strength λ) is also presented for XH2, XH, and XH4 molecules or molecular fragments. Calculations of X-H bond angles for a number of molecules show that the results from our equations are in excellent agreement with the experimental values. Also we can extract the information of relative magnitude of bond coupling force field.
