SIMULATION OF NONDYNAMICAL CORRELATION IN DENSITY FUNCTIONAL CALCULATIONS BY THE OPTIMIZED FRACTIONAL ORBITAL OCCUPATION APPROACH : APPLICATION TO THE POTENTIAL ENERGY SURFACES OF O3 AND SO2
SIMULATION OF NONDYNAMICAL CORRELATION IN DENSITY FUNCTIONAL CALCULATIONS BY THE OPTIMIZED FRACTIONAL ORBITAL OCCUPATION APPROACH : APPLICATION TO THE POTENTIAL ENERGY SURFACES OF O3 AND SO2
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优化分数轨道占据法模拟密度泛函计算中的非动力学相关性：在O3和SO2势能面中的应用
DOI：
10.1063/1.472307
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发表时间：
1996
影响因子：
4.4
通讯作者：
W. Schwarz
中科院分区：
文献类型：
--
作者：
S. Wang;W. Schwarz
如果作为N个几何参数的函数的占据轨道和空轨道的能量以不同的方式变化，则诸如密度泛函之类的单一行列式方法可能违反Aufbau原理和不交叉规则，即，相同对称性的状态可以在（N-1）维参数子空间中交叉。如果用费米能级上轨道占据分数的混合系综密度来模拟占主导地位的组态混合，那么密度泛函方法就能恢复避免的交叉，正如Dunlap和Mei首先指出的那样[J. Chem. Phys. 78，4997（1983）]。然而，目前的密度泛函方法不能恢复（N-2）维子空间中的非避免交叉。密度泛函分数占据数方法产生合理的过渡到开放的基态的O3和SO2分子的环状的途径。
If the energies of occupied and empty orbitals as functions of N geometric parameters vary in different manners, single determinantal approaches such as the density functional ones may violate the Aufbau principle and the noncrossing rule, i.e., states of the same symmetry may cross in an (N−1)‐dimensional parameter subspace. If dominant configuration mixing is simulated by a mixed ensemble density with fractional occupation numbers of the orbitals at the Fermi level, the density functional approaches recover the avoided crossing, as first pointed out by Dunlap and Mei [J. Chem. Phys. 78, 4997 (1983)]. However, present density functional approaches do not recover the nonavoided crossing in (N−2)‐dimensional subspaces. The density functional–fractional occupation number approach yields reasonable pathways for the transition from the cyclic to the open ground state of O3 and SO2 molecules.