Hoạt động
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Seminar
| Seminar Vật lý lý thuyết và Vật lý tính toán:
| | Tên báo cáo | Theoretical study of the fragmentation of small neutral carbon clusters Cn and hydrocarbons CnH
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| Người trình bày | TS. Đỗ Thị Nga
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| Cơ quan | Trung tâm Vật lý Tính toán, Viện Vật lý
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| Ngày | Thứ Ba, 03-01-2012
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| Giờ | 10:00 AM
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| Địa điểm | Phòng họp tầng 1, Viện Vật lý, 10 Đào Tấn, Ba Đình, Hà Nội
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| Tóm tắt | This work concerns with the theoretical study of the fragmentation of small neutral carbon clusters Cn and hydrocarbons CnH by a statistical model of Microcanonical Metropolis Monte Carlo (MMMC). This model describes, in constraint of fixed energy, the phase space associated with all the degrees of freedom accessible to the system (partitions of the mass, the movements of translation and rotation, spin and angular momentum of fragments). The basic ingredients of the model MMMC (geometries, dissociation energies, harmonic frequencies…) must be obtained for both the parent cluster and the fragments by a same ab initio calculation. These were calculated in implementation of the density functional theory (DFT) at the level of calculation B3LYP/6-311+G(3df). The results obtained on the appearance probability of the fragmentation channels according to the excitation energy, were compared with the experimental data obtained with the Tandem at Orsay what allowed us to find a distribution of energy deposited in the parent cluster during the collision. All the branching ratios of the fragmentation channels of Cn (n ≤ 9) and CnH (n ≤ 4) were measured following electron capture of high velocity (v = 2.6 u.a.) Cn+ and (v = 4.5 u.a.) CnH+ projectiles in collision with helium atoms. The distribution of energy must be adjusted so that the experimental measures are optimally reproduced in involvement two algorithms: Non-Negative Least Squares and backtracing Bayesien. The comparison of the theoretical and experimental probabilities shows a good global agreement. A particularly interesting result extracted by the comparison theory/experiment is the appearance of the distributions pointed of excitation energy.
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