scholarly journals Second-order nonadiabatic couplings from time-dependent density functional theory: Evaluation in the immediate vicinity of Jahn-Teller/Renner-Teller intersections

2011 ◽  
Vol 135 (7) ◽  
pp. 074101 ◽  
Author(s):  
Chunping Hu ◽  
Osamu Sugino ◽  
Kazuyuki Watanabe
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Second Order ◽  
Time Dependent ◽  
Functional Theory ◽  
Theory Evaluation ◽  
Jahn Teller ◽  
Dependent Density

THE INVESTIGATION ON ELECTRONIC STRUCTURE AND SECOND-ORDER NONLINEAR OPTICAL PROPERTIES OF II–VI SEMICONDUCTOR CLUSTERS BY TIME-DEPENDENT DENSITY FUNCTIONAL THEORY

2007 ◽  
Vol 06 (03) ◽  
pp. 585-594 ◽  
Author(s):  
YONGQING QIU ◽  
XIAOHONG WANG ◽  
YICHUN LIU ◽  
GUOCHUN YANG ◽  
HUI CHEN
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Second Order ◽  
Time Dependent ◽  
Basis Sets ◽  
Functional Theory ◽  
Nlo Properties ◽  
Semiconductor Clusters ◽  
Dependent Density

Time-dependent density functional theory (TD-DFT) formalism is employed to calculate the electronic spectra of A 3 B 3 II–VI semiconductor clusters based on the geometrical structures optimized at DFT-B3LYP level. Moreover, their second-order nonlinear optical (NLO) properties are performed by TD-B3LYP combined with sum-over-states (SOS) formula. The calculation results indicate that it is necessary to consider the effective core potential and electron correlation effects when the basis sets are chosen for the heavy atoms. In addition, the results show that the transition energies and HOMO–LUMO gaps of the A 3 B 3 II–VI semiconductor clusters decrease, while the second-order nonlinear optical responses increase with the increasing of VI-group ionic radius. As a result, the SOS formula is valuable to calculate the βμ in the summation of 120 states. Meanwhile, charge transfers from the π bonding to π anti-bonding orbitals between II and VI group atoms significantly contribute to the second-order NLO properties.

Benchmark of Simplified Time-Dependent Density Functional Theory for UV-Vis Spectral Properties of Porphyrinoids

2019 ◽  
Author(s):  
Kamal Batra ◽  
Stefan Zahn ◽  
Thomas Heine
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Large Scale ◽  
Absolute Error ◽  
Time Dependent ◽  
Basis Set ◽  
Basis Sets ◽  
Functional Theory ◽  
Framework Materials ◽  
Dependent Density

<p>We thoroughly benchmark time-dependent density- functional theory for the predictive calculation of UV/Vis spectra of porphyrin derivatives. With the aim to provide an approach that is computationally feasible for large-scale applications such as biological systems or molecular framework materials, albeit performing with high accuracy for the Q-bands, we compare the results given by various computational protocols, including basis sets, density-functionals (including gradient corrected local functionals, hybrids, double hybrids and range-separated functionals), and various variants of time-dependent density-functional theory, including the simplified Tamm-Dancoff approximation. An excellent choice for these calculations is the range-separated functional CAM-B3LYP in combination with the simplified Tamm-Dancoff approximation and a basis set of double-ζ quality def2-SVP (mean absolute error [MAE] of ~0.05 eV). This is not surpassed by more expensive approaches, not even by double hybrid functionals, and solely systematic excitation energy scaling slightly improves the results (MAE ~0.04 eV). </p>

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