scholarly journals Second harmonic generation and electro-optical Pockels effect of 1- and 3-nitro-6-azabenzo[a]pyrene N-oxide isomers: A Hartree–Fock and Coulomb-attenuating density functional theory investigation

2014 ◽  
Vol 126 (3) ◽  
pp. 701-710 ◽  
Author(s):  
ANDREA ALPARONE
2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Andrea Alparone

The static and dynamic electronic (hyper)polarizabilities of the equilibrium conformations of 2,2′-bithiophene (anti-gauche and syn-gauche) were computed in the gas phase. The calculations were carried out using Hartree-Fock (HF), Møller-Plesset second-order perturbation theory (MP2), and density functional theory methods. The properties were evaluated for the second harmonic generation (SHG), and electrooptical Pockels effect (EOPE) nonlinear optical processes at the typical λ=1064 nm of the Nd:YAG laser. The anti-gauche form characterized by the S–C2–C2′–S dihedral angle of 137° (MP2/6-311G**) is the global minimum on the potential energy surface, whereas the syn-gauche rotamer (S–C2–C2′–S = 48°, MP2/6-311G**) lies ca. 0.5 kcal/mol above the anti-gauche form. The structural properties of the gauche structures are rather similar to each other. The MP2 electron correlation effects are dramatic for the first-order hyperpolarizabilities of the 2,2′-bithiophenes, decreasing the HF values by ca. a factor of three. When passing from the anti-gauche to the syn-gauche conformer, the static and frequency-dependent first-order hyperpolarizabilities increase by ca. a factor of two. Differently, the electronic polarizabilities and second-order hyperpolarizabilities of these rotamers are rather close to each other. The syn-gauche structure could be discriminated from the anti-gauche one through its much more intense SHG and EOPE signals.


2011 ◽  
Vol 1370 ◽  
Author(s):  
E. Luppi ◽  
H. Hübener ◽  
M. Bertocchi ◽  
E. Degoli ◽  
S. Ossicini ◽  
...  

ABSTRACTWe developed an ab initio formalism based on Time-Dependent Density-Functional Theory for the calculation of the second-order susceptibility Χ(2) (Luppi et al. J. Chem. Phys. 132, 241104(2010)). We apply this formalism to the calculation of second-harmonic generation spectra of hexagonal SiC polytypes, ZnGeP2 (ZGP) and GaP. Starting from the independent-particle approximation, we include manybody effects, such as quasiparticle via the scissors operator, crystal local fields and excitons. We consider two different types of kernels: the ALDA and the “long-range” kernel. We analyze the effects of the different electron-electron descriptions in the spectra, finding good agreement with experiments.


2018 ◽  
Vol 20 (43) ◽  
pp. 27658-27667 ◽  
Author(s):  
Claire Tonnelé ◽  
Benoît Champagne ◽  
Luca Muccioli ◽  
Frédéric Castet

Nonlinear optical properties of Stenhouse photoswitches are computed using time-dependent density functional theory, revealing large variations in the amplitude and symmetry of the second harmonic generation responses.


2012 ◽  
Vol 11 (01) ◽  
pp. 209-221 ◽  
Author(s):  
ASLI KARAKAŞ ◽  
ZİYA ERDEM KOÇ ◽  
MICHAELA FRIDRICHOVÁ ◽  
PETR NĚMEC ◽  
JAN KROUPA

p-nitrophenylazoaniline (1) belongs to the family of compounds with conjugated bonds and delocalized π-electrons, structurally similar to the well known push-pull compound Disperse Red 1 (DR1).1 Due to the assembly of the molecule, nonlinear optical (NLO) properties are expectable and can be more or less accurately predicted. To estimate the potential for second-order NLO properties, the electric dipole moment (μ), dispersion-free dipole polarizabilities (α) and first hyperpolarizabilities (β) have been determined by density functional theory (DFT) quantum chemical calculations at B3LYP/ 6-311 + G(d, p) level. According to the computation results, the synthesized compound exhibits non-zero β values and it might have second-order NLO behavior. Title compound has been synthesized and characterized by FT-IR, 1H-NMR and UV-Vis spectroscopies. The maximum one-photon absorption (OPA) wavelengths were estimated to be shorter than 450 nm by quantum mechanical computations using the configuration interaction (CI) method. The same result was achieved by UV-Vis spectra measurements, whereas the compound exhibited good optical transparency to the visible light. Quantitative measurements of second harmonic generation (SHG) at 800 nm and 1064 nm have been performed. The relative efficiency comparable with that of KDP (kalium diphosphate) has been observed with the exciting wavelength of 1064 nm, while the other wavelength led to strong absorption of produced light by the sample. In the following more detailed study on frequency-dependent first hyperpolarizabilities using time-dependent Hartree–Fock (TDHF) method have been computed at the wavelengths used in SHG measurements.


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