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本帖最后由 冰释之川 于 2017-2-21 11:25 编辑
另外接3L liyuanhe211，HOMO/LUMO gap如果采用DFT算，则HF成分越高的泛函，算出来的gap越大。(通常用B3LYP、B3PW91泛函算是最合适不过了，参考《简谈量子化学计算中DFT泛函的选择》) 。此外，optical gap 、HOMO/LUMO gap和foundmental gap (IP减去EA的值)这三个gap在我们计算化学人看来必须要分清楚，绝大多数情况下都不等价的！具体参见Bredas, J.-L. Mind the Gap! Mater. Horiz. 2014, 1, 17-19.
附上文摘：
（1）The calculated HOMO–LUMO gap, i.e., the difference between the calculated HOMO and LUMO energy levels, only provides an approximation to the fundamental gap;
（2）The fundamental gap is defined as the difference between the ionization potential and electron affinity: E(fund) = IP - EA. Experimentally, it can be determined via a combination of gas-phase ultraviolet photoelectron spectroscopy and electron attachment spectroscopy; at the computational level, it requires the comparison between the total energy of the N-electron ground state and that of the (N+1)-electron state (to determine EA) or that of the (N-1)-electron state (to determine IP)
（3）The optical gap of a molecule corresponds to the energy of the lowest electronic transition accessible via absorption of a single photon. (Note that in both molecule and material cases, our discussion will assume that the lowest transition involves the first excited state and neglects the more complex instances where this state is optically forbidden).
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发表于 Post on 2017-2-20 23:02:31
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