Dissertation > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Structural Chemistry > Chemical bond theory

C_3-Rg system , the intermolecular potential energy surface and theoretical study of vibrational levels

Author SunChuanZhi
Tutor ChenDeZhan;ZhangGuiQiu
School Shandong Normal University
Course Physical and chemical
Keywords Intermolecular interaction Potential surface vibrational spectra DVR C3-Rg
CLC O641.1
Type Master's thesis
Year 2007
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During the last decades,C3 has attracted a lot of experimental and theoretical attention, and meanwhile it is accepted that the singlet ground state has a linear geometry with a very soft-bending mode. In recent years, the study of the weak intermolecular interaction of vdW complexes has attracted considerable attention. In terms of experimental , Hsu’s group recorded lots of significative C3-complex spectra with LIF excitation and emission techniques. But there is no report about intermolecular interaction between C3 and Rg in theoretical aspect.Ab initio intermolecular potential energy surfaces (PES) calculation on the C3-Rg complexes with C3 at its single ground state are reported using a supermolecular approach. The calculation was performed at the coupled-cluster [CCSD(T)] level, with the full counterpoise correction for the basis set superposition error and a large basis set including midpoint bond functions.The potential energy surfaces (PES) of C3-Rg is very anisotropic. It is found that the atom Rg has a large scale swing in the plane ,the scale become more and more smaller from He to Kr .The intermolecular force is more and more intense , and the depth of the well become deeper. The T-shaped minimum is the global minimum. The depth of the well (Vm) is -25.542cm-1、-60.618 cm-1、-156.863 cm-1、-192.710 cm-1 from He to Kr . The CCSD(T) potential energy surface (PES) of C3-Ne is a little different from the other three potential energy surfaces. The second minima is found inθ=10o andθ=170o.In order to validate the veracity of the calculation, we reconstruct the potential energy surface of C3-Ne at MP4/cc-PVQZ level. We found that the The second minima of the C3-Ne is disappeared inθ=10o andθ=170o.So the reason why the PES of C3-Ne is different from the other three potential energy surfaces is that the CCSD(T)/aug-cc-PVTZ is not match to the Ne atom. The two-dimensional discrete variable representation (DVR) method is employed to calculate the vibrational energy levels and the wave functions for C3-Rg at its ground and excited states. The vibrational calculations show that the ab initio potential supports several vibrational bound states. The number of vibrational bound states become more .We also obtain the energy between the ground state and the first excited state ,and the numerical value is more and more larger. The calculated values are in good agreement with the observed results. In additional , the wave functions which are used to designate vibrational bound states are also obtained .This work should provide useful information for observation of the spectroscopy and further studies of the C3-Ar van der Waals systems.

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