研究目的
To computationally study the lifetimes of the ion-pair n1Rt g (n = 3–6) states of lithium dimer using ab initio methods and to test these methods by calculating lifetimes for the A1Rt u state.
研究成果
The ab initio calculations successfully reproduced electronic transition dipole moments and potential curves for lithium dimer ion-pair states, showing good agreement with experimental data for tested cases like the A1Rt u state. Lifetimes of the ion-pair states exhibit variations correlated with avoided crossings and interactions with the ion-pair potential, highlighting the impact of ionic-covalent interactions on radiative properties. The study provides insights into the behavior of these states and validates the computational approach, suggesting its utility for similar systems, with recommendations for future work to include non-radiative decay mechanisms.
研究不足
The computational methods may have limitations in accuracy due to basis set choices and approximations in the full CI method. The study does not account for non-radiative processes like predissociation, which could affect lifetimes, especially for states above certain atomic limits. The potential curves for some states (e.g., 51Rt g and 61Rt g) had to be recalculated due to coarse grids in previous works, indicating sensitivity to computational parameters.
1：Experimental Design and Method Selection:
The study uses ab initio computational methods, specifically the full configuration-interaction (CI) method, to calculate electronic transition dipole moment functions and potential energy curves. Lifetime calculations incorporate both bound-bound and bound-free transitions using programs like LEVEL 8.0 and BCONT for solving the radial Schr?dinger equation and calculating transition intensities.
2：0 and BCONT for solving the radial Schr?dinger equation and calculating transition intensities.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: The focus is on the lithium dimer (Li2), with potential curves derived from a combination of experimental data (e.g., from RKR and IPA methods) and ab initio calculations. Specific states studied include n1Rt g (n=3-6), A1Rt u, B1Pu, and 21Rt u.
3：List of Experimental Equipment and Materials:
No physical equipment is used as this is a computational study; it relies on software tools and theoretical models.
4：Experimental Procedures and Operational Workflow:
Ab initio calculations are performed over a range of internuclear distances (4-40 atomic units) to obtain potential energy curves and transition dipole moments. Lifetimes are computed by integrating Einstein coefficients for radiative decays using numerical methods from the referenced programs.
5：Data Analysis Methods:
Data analysis involves comparing calculated lifetimes with experimental values where available, using statistical agreement metrics (e.g., differences of 1-2%), and visualizing results through plots of Einstein coefficients and lifetimes versus vibrational levels.
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