The molecular dipole moment of the non-linear optical 3-methyl 4-nitropyridine N-oxide molecule: X-ray diffraction and semi-empirical studies

1996 ◽  
Vol 6 (7) ◽  
pp. 1123 ◽  
Author(s):  
Fodil Hamzaoui ◽  
Fran�ois Baert ◽  
Joseph Zyss
1999 ◽  
Vol 55 (5) ◽  
pp. 965-967 ◽  
Author(s):  
Philip Coppens ◽  
Anatoliy Volkov ◽  
Yuriy Abramov ◽  
Tibor Koritsanszky

The error in the molecular dipole moment as derived from accurate X-ray diffraction data is shown to be origin dependent in the general case. It is independent of the choice of origin if an electroneutrality constraint is introduced, even when additional constraints are applied to the monopole populations. If a constraint is not applied to individual moieties, as is appropriate for multicomponent crystals or crystals containing molecular ions, the geometric center of the entity considered is a suitable choice of origin for the error treatment.


2003 ◽  
Vol 59 (11) ◽  
pp. i107-i108 ◽  
Author(s):  
Tongqing Sun ◽  
Feng Pan ◽  
Ruji Wang ◽  
Guangqiu Shen ◽  
Xiaoqing Wang ◽  
...  

The title compound, tricadmium trizinc tetraborate, Cd3Zn3(BO3)4, is a new non-linear optical (NLO) crystal and its structure has been determined by single-crystal X-ray diffraction. This compound is composed of planar [BO3]3− groups sharing O atoms with CdO4 or ZnO4 tetrahedra. The BO3 triangles are located on threefold axes and are arranged with nearly the same orientation. The Cd and Zn atoms are disordered on the same site in the proportion 1:1. A strong second harmonic generation of Nd:YAG laser radiation (λ = 1064 nm) has been observed for a crystal of the title compound.


1998 ◽  
Vol 51 (9) ◽  
pp. 813 ◽  
Author(s):  
Daniel E. Lynch ◽  
Niraj Mistry ◽  
Graham Smith ◽  
Karl A. Byriel ◽  
Colin H. L. Kennard

The molecular adducts of indole-3-acetic acid (iaa) and indole-2-carboxylic acid (ica) with 5-nitroquinoline (nq), [(iaa)(nq)2] (1) and [(ica)(nq)] (2), have been prepared and characterized by X-ray diffraction and spectroscopic methods. Both examples involve charge transfer as well as a network of hydrogen-bonding interactions. Thin films of compound (2), and other similar adduct complexes of ica, can be prepared by thermal evaporation techniques and in this form exhibit a weak second-order non-linear optical signal. However, these films display poor optical quality and, without improvement, are not suitable for any potential non-linear optical applications.


1996 ◽  
Vol 52 (2) ◽  
pp. 260-265 ◽  
Author(s):  
D. L. Corker ◽  
A. M. Glazer

The crystal structure of lead tetraborate, PbO.2B2O3, has been refined using single-crystal X-ray diffraction data (Mo Kα radiation, λ = 0.71069 Å). Crystal data at room temperature: Mr = 362.43, orthorhombic, P21 nm (C 7 2v ), a = 4.251 (2), b = 4.463 (3), c = 10.860 (3) Å, V = 206.04 Å3 with Z = 2, μ = 402.6 cm−1, Dx = 5.88 Mg m−3, F(000) = 316, final R = 0.022, wR = 0.025 over 655 reflections with I > 2.5σ(I). Atomic coordinates are in general agreement with those previously reported for the isostructural compound, SrO.2B2O3, by Perloff & Block [Acta Cryst. (1966), 20, 274–279]. All the borons are tetrahedrally coordinated with a three-dimensional network formed from O atoms that are common to either two or three tetrahedra. The tetrahedra show deformation because the B—O bonds involving the two-coordinated O atoms are much shorter than those involved with three-coordinated O atoms. The Pb atoms are situated in empty tunnels running along [010] left by the network of tetrahedra. The Pb atoms display a highly asymmetric distribution of Pb—O bonding, with the five shortest bonds covering the range 2.483 (5)–2.664 (5) Å, being all situated to one side of the Pb atom. Preliminary investigations of the non-linear optical behaviour of lead tetraborate are also discussed. The results indicate that doping with barium should lead to a new non-linear optical material that is both phase-matchable and has a high optical non-linearity.


2001 ◽  
Vol 57 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Elizabeth A. Zhurova ◽  
A. Alan Pinkerton

The electron density and related properties of the quasi-stable β form of 5-nitro-2,4-dihydro-3H-1,2,4-triazol-3-one (NTO; space group P21/c) have been determined from a low-temperature [100 (1) K] X-ray diffraction experiment. Intensities were measured with a 2K CCD Bruker diffractometer using Ag Kα radiation. Two detector settings, several φ settings, 0.3° ω scans and 160 s exposure time per frame gave R int = 0.0215 for 68 989 (4080 unique) reflections and (sin θ/λ)max = 1.23 Å−1. The Hansen–Coppens [Acta Cryst. (1978), A34, 909–921] multipole model as implemented in the XD program gave R = 0.0333 (all reflections), which allowed calculation of the electron density, Laplacian and electrostatic potential distributions. The bonding (3,−1) critical points and the molecular dipole moment of 3.2 (1) D were also obtained. Chemical bonding in the molecule is discussed.


2020 ◽  
Author(s):  
Bowen Han ◽  
Christine Isborn ◽  
Liang Shi

Partial atomic charges provide an intuitive and efficient way to describe the charge distribution and the resulting intermolecular electrostatic interactions in liquid water. Many charge models exist and it is unclear which model provides the best assignment of partial atomic charges in response to the local molecular environment. In this work, we systematically scrutinize various electronic structure methods and charge models (Mulliken, Natural Population Analysis, CHelpG, RESP, Hirshfeld, Iterative Hirshfeld, and Bader) by evaluating their performance in predicting the dipole moments of isolated water, water clusters, and liquid water as well as charge transfer in the water dimer and liquid water. Although none of the seven charge models is capable of fully capturing the dipole moment increase from isolated water (1.85 D) to liquid water (about 2.9 D), the Iterative Hirshfeld method performs best for liquid water, reproducing its experimental average molecular dipole moment, yielding a reasonable amount of intermolecular charge transfer, and showing modest sensitivity to the local water environment. The performance of the charge model is dependent on the choice of the density functional and the quantum treatment of the environment. The computed molecular dipole moment of water generally increases with the percentage of the exact Hartree-Fock exchange in the functional, whereas the amount of charge transfer between molecules decreases. For liquid water, including two full solvation shells of surrounding water molecules (within about 5.5 A of the central water) in the quantum-chemical calculation converges the charges of the central water molecule. Our final pragmatic quantum-chemical charge assigning protocol for liquid water is the Iterative Hirshfeld method with M06-HF/aug-cc-pVDZ and a quantum region cutoff radius of 5.5 A.<br>


1994 ◽  
Vol 49 (7-8) ◽  
pp. 785-789 ◽  
Author(s):  
K. Fukushima ◽  
M. Murofushi ◽  
M . Oki ◽  
K. Igarashi ◽  
J. Mochinaga ◽  
...  

Abstract The short range structure of molten NaHSO4(I) and KHSO4(II) was estimated by X-ray diffraction. The polyatomic anion, HSO4-, in both molten salts was found to have a distorted tetrahedral structure in which the bond lengths of S-O and S-OH were 1.45 Å and 1.53 Å in (I) and 1.46 Å and 1.56 Å in (II), respectively. The coordination number of the Na+ or K+ around the HSO4- was evaluated to be about unity. The semi-empirical molecular orbital calculations by the MNDO-MOPAC method were applied to the determination of the intraionic structure of the H S 0 4 and the bond lengths of S-O and S -OH were computed to be 1.528 Å and 1.666 Å, respectively, supporting qualitatively that the HSO4- forms a rather distorted tetrahedron.


RSC Advances ◽  
2016 ◽  
Vol 6 (101) ◽  
pp. 99139-99148 ◽  
Author(s):  
Soma Adhikari ◽  
Tanusree Kar ◽  
Saikat Kumar Seth

A new NLO material namely di-valine maleic (VM) was synthesized and characterized by X-ray diffraction analysis. The SHG efficiency of VM was investigated and dipole moment, polarizability, first order hyperpolarizability were calculated by DFT method.


Sign in / Sign up

Export Citation Format

Share Document