Let there be Light in Tight Binding

1997 ◽  
Vol 491 ◽  
Author(s):  
P. Vogl ◽  
M. Graf ◽  
A. Görling
Keyword(s):  
Solid State ◽  
Electromagnetic Fields ◽  
Optical Constants ◽  
Tight Binding ◽  
Time Dependent ◽  
High Magnetic Fields ◽  
Gauge Invariant ◽  
Polar Materials ◽  
Wide Range ◽  
Tight Binding Method

ABSTRACTEmpirical tight-binding theory is generalized to incorporate time-dependent electromagnetic fields in a systematic and gauge-invariant manner that does not introduce any extra adjustable parameters. It is shown that this approach successfully predicts a wide range of solid state properties that have not been accessible within the tight binding method so far. We present applications such as optical constants, luminescence in heterostructures, properties in ultra-high magnetic fields and lattice dynamics in polar materials.

scholarly journals Time-Dependent Long-Range Corrected Density-Functional Tight-Binding Method Combined with the Polarizable Continuum Model

2019 ◽  
Author(s):  
Yoshio Nishimoto
Keyword(s):  
Excited State ◽  
Long Range ◽  
Continuum Model ◽  
Density Functional ◽  
Tight Binding ◽  
Polarizable Continuum Model ◽  
Time Dependent ◽  
Dual Emission ◽  
Tight Binding Method ◽  
Polarizable Continuum

In this study, excited-state free energies and geometries were efficiently evaluated using a linear-response time-dependent long-range corrected density-functional tight-binding method integrated with the polarizable continuum model (TD-LC-DFTB/PCM). Although the LC-DFTB method required the evaluation of the exchange-type term, which was moderately computationally expensive, a single evaluation of the excited-state gradient for a system consisting of more than 1000 atoms in a vacuum was completed within 30 minutes using one CPU core. Benchmark calculations were conducted for 3-hydroxy avone, which exhibits dual emission: the absorption and enol-form emission wavelengths calculated by TD-LC-DFTB/PCM agreed well with those predicted based on density functional theory using a long-range corrected functional; however, there was a large error in the predicted keto-form emission wavelength. Further benchmark calculations for more than 20 molecules indicated that the conventional TD-DFTB method underestimated the absorption and 0-0 transition energies compared with those which were measured experimentally while the TD-LC-DFTB method systematically overestimated these metrics. Nevertheless, the agreement of the results of the TD-LC-DFTB method with those obtained by the CAM-B3LYP method demonstrates the potential of the TD-LC-DFTB/PCM method. Moreover, changing the range-separation parameter to 0.15 minimized this deviation.<br>

Time-Dependent Extension of the Long-Range Corrected Density Functional Based Tight-Binding Method

2017 ◽  
Vol 13 (4) ◽  
pp. 1737-1747 ◽  
Author(s):  
Julian J. Kranz ◽  
Marcus Elstner ◽  
Bálint Aradi ◽  
Thomas Frauenheim ◽  
Vitalij Lutsker ◽  
...  
Keyword(s):  
Long Range ◽  
Density Functional ◽  
Tight Binding ◽  
Time Dependent ◽  
Tight Binding Method

scholarly journals Time-Dependent Long-Range Corrected Density-Functional Tight-Binding Method Combined with the Polarizable Continuum Model

2019 ◽  
Author(s):  
Yoshio Nishimoto
Keyword(s):  
Excited State ◽  
Long Range ◽  
Continuum Model ◽  
Density Functional ◽  
Tight Binding ◽  
Polarizable Continuum Model ◽  
Time Dependent ◽  
Dual Emission ◽  
Tight Binding Method ◽  
Polarizable Continuum

In this study, excited-state free energies and geometries were efficiently evaluated using a linear-response time-dependent long-range corrected density-functional tight-binding method integrated with the polarizable continuum model (TD-LC-DFTB/PCM). Although the LC-DFTB method required the evaluation of the exchange-type term, which was moderately computationally expensive, a single evaluation of the excited-state gradient for a system consisting of more than 1000 atoms in a vacuum was completed within 30 minutes using one CPU core. Benchmark calculations were conducted for 3-hydroxy avone, which exhibits dual emission: the absorption and enol-form emission wavelengths calculated by TD-LC-DFTB/PCM agreed well with those predicted based on density functional theory using a long-range corrected functional; however, there was a large error in the predicted keto-form emission wavelength. Further benchmark calculations for more than 20 molecules indicated that the conventional TD-DFTB method underestimated the absorption and 0-0 transition energies compared with those which were measured experimentally while the TD-LC-DFTB method systematically overestimated these metrics. Nevertheless, the agreement of the results of the TD-LC-DFTB method with those obtained by the CAM-B3LYP method demonstrates the potential of the TD-LC-DFTB/PCM method. Moreover, changing the range-separation parameter to 0.15 minimized this deviation.<br>

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