Linear and nonlinear optical properties of 3-nitroaniline (m-NA) and 4-nitroaniline (p-NA) crystals: A DFT/TDDFT study |
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| Institution: | 1. Department of Physics, Banaras Hindu University, Varanasi 221005, U.P., India;1. Key Labs of Nanodevices and Applications, Chinese Academy of Sciences, Suzhou 215123, China;2. Division of Nanodevices and Related Materials, Suzhou Institute of Nanotech and Nanobionics, Chinese Academy of Sciences, Suzhou 215123, China;3. Wenzheng College of Soochow University, Suzhou 215006, China;4. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China;5. College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006, China;1. Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1521 Budapest, Hungary;2. Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, 1519 Budapest, Hungary;3. MTA-BME Organic Chemical Technology Research Group, Hungarian Academy of Sciences, 1521 Budapest, Hungary;4. Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1111 Budapest, Hungary;1. A.P. Vinogradov Institute of Geochemistry SB RAS, 1a Favorski Str., Irkutsk 664033, Russia;2. Irkutsk State Technical University, 83 Lermontov Str., Irkutsk 664074, Russia;3. Irkutsk State University, 20 Gagarin Blvd., Irkutsk 664003, Russia |
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| Abstract: | We have studied the electronic structure and optical responses of 3-nitroaniline and 4-nitroaniline crystals within the framework of density functional theory (DFT). In addition, the excitonic effects are investigated by using the recently published bootstrap exchange-correlation kernel within the time dependent density functional theory (TDDFT) framework. Our calculations based on mBJ approximation yield the indirect band gap for both crystals, but the larger one for m-NA. Due to the excitonic effects, the TDDFT calculations gives rise to the enhanced and red-shifted spectra (compared to RPA). Due to the weak intermolecular interactions, band-structure calculations yield bands with low dispersion for both crystals. This study shows that the substituent groups play an important role in the top of valence band and the bottom of conduction band. Due to the linear structure of p-NA molecule, the highest peaks are located in the optical spectra of p-NA crystal, while m-NA has more sharp peaks, especially at lower energies. Both DFT and TDDFT calculations for the energy loss spectra show plasmon peaks around 27 and 28 eV for p-NA and m-NA, respectively. Due to the non-centrosymmetric structure of m-NA crystal, we also have reported its nonlinear spectra and the 2ω/ω intra-band and inter-band contributions to the dominant susceptibilities. Findings indicate the opposite signs for these contributions, especially at higher energies. The comparison between nonlinear spectra and the linear spectra (as a function of both ω and 2ω) reveals the significant resemblance between linear and nonlinear patterns. In addition to the reasonable agreement between our results with experimental data, this study reveals the spectral similarities between crystalline susceptibility and molecular polarizability. |
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| Keywords: | Organic compounds Ab initio calculations Electronic structure Optical properties |
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