Calculation of the nonlinear optical properties of molecules

Alparone

et al. 2008

Biophysical Chemistry

The geometries, relative energies, gas-phase static and dynamic dipole polarizabilities of the two most stable neutral forms and of the zwitterionic form of the twenty naturally occurring amino acids have been obtained by Density Functional and conventional ab initio HatreeFock theories using correlation consistent basis sets. Mean electronic polarizabilities (<α e >s) are encompassed in the 40-160 a.u. range and are little dependent on the amino acid framework conformation, structure and conformation. The relation between <α e > and the number of electrons in the molecule makes to classify the amino acids as one of the most polarizable family of compounds. Calculated <α e > values of the neutral forms linearly relate to the molecular volume and molecular hardness as well as, rather unexpectedly, with the experimental values in water solution, where amino acids are known to be in a zwitterionic form. Vibrational polarizabilities amount to 15-45 a.u.. They come essentially from the lowfrequency angular deformation modes of the -OH and -NH 2 groups.

“…[15] using an electric field strength of 0.005 a.u.. The accuracy of this approach was checked at HF level by comparing α e values obtained by both analytical and FF procedures.…”

Section: Computational Proceduresmentioning

confidence: 99%

Electronic and vibrational polarizabilities of the twenty naturally occurring amino acids

Alparone

et al. 2008

Biophysical Chemistry

Int J of Quantum Chemistry

“…In this case, as a first step the wave functions for the ground and excited states are generated by solving the SCF equations of the approximate CNDO/S Hamiltonian according to the parameterization of Del Bene and Jaffe [23] including configuration interaction. Next, the optical tensors are obtained from an SOS [24] procedure within the framework of time-dependent perturbation theory. The SOS was performed with all electronic states generated by singly exciting all electrons from the 40 highest occupied MOs to the 40 lowest unoccupied MOs with respect to the ground state.…”

Section: Technical Detailsmentioning

confidence: 99%

“…a X-ray [24] structure and NLO computed at the B3LYP/6-311G level. b B3LYP/6-311G structure and NLO computed at the B3LYP/6-311G level.…”

mentioning

confidence: 99%

Investigation of NLO properties of substituted (M)‐tetrathia‐[7]‐helicenes by semiempirical and DFT methods

Daul

Ciofini

Weber

2002

ABSTRACT:In this article, we propose a theoretical study of static and dynamic polarizability ␣, first hyperpolarizability ␤, and second hyperpolarizability ␥ of substituted (M)-tetrathia-[7]-helicenes. Both a semiempirical approach, in the case of static and dynamic properties, and density functional theory, in the case of static electric properties, were used. The nonlinear optical (NLO) properties of a set of 10 molecules were investigated to predict the couple of donor-acceptor substituents that could best enhance the optical properties of (M)-tetrathia-[7]-helicene.

“…The moderate neglect of differential overlap (MNDO Hamiltonian) was adopted with AM1. 30,31 First, the molecular geometry was optimized, and then the electronic polarizability was calculated. The polarizability anisotropy Da was calculated from the following equation:…”

Section: Other Measurementsmentioning

confidence: 99%

Design and synthesis of a zero-photoelastic birefringence polymer with a high glass-transition temperature by a random copolymerization method

Shafiee

Tagaya

Koike

2011

Polym J

We designed and synthesized a zero-photoelastic birefringence polymer that had a high glass-transition temperature (T g ) by introducing trans-stilbene units into the side chains of the copolymer by a random copolymerization method. The concentration of the trans-stilbene units required to compensate for photoelastic birefringence in the random copolymer was lower than that required in a polymer prepared by an anisotropic molecule dopant method, because the presence of an anisotropic moiety in the side chain of the polymer has a greater effect than an anisotropic molecule doped in the polymer. Furthermore, the polymer with trans-stilbene units in side chains showed a higher T g than the polymer containing an anisotropic dopant. We conclude that the introduction of an anisotropic molecule of a similar or larger size to trans-stilbene into the side chain gives a polymer with a high T g .