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Atomic Response Theory Developed on the Origin of Nonlinear Optical Materials

Nonlinear optical (NLO) crystals are the key materials for laser science and technology as they can change the frequency of laser beam and modulate it in amplitude and phase through the process of second harmonic generation (SHG). No substantial theoretical progress on NLO material has been made which frustrated the search for new NLO materials since 1978.

The new approach to explore the structure-property relationship of materials is to use the concept of material genome or functional motif. However, a mature ansatz for revealing the origin of SHG phenomenon on the basis of general theoretical principles and such concepts of a material is still not available.

In a recent study published in Angew. Chem. Int. Ed., the research group led by Prof. DENG Shuiquan from Fujian Institute of Research on the Structure of Matter of Chinese Academy of Sciences developed a new atomic response theory on the origin of NLO material by inventing a universal partial response functional method.

Researchers investigated the origin of the unusual large SHG effect of the deep-ultraviolet NLO material LiCs2PO4 (LCPO) as an application by using the first principles calculations and theoretical model analysis.

The SHG response of LCPO was shown dominated by the metal-cation-centered groups CsO6 and LiO4, not by the nonmetal-cation-centered groups PO4 as expected from the existing models and theories.

They then found that the occupied orbitals O-2p and Cs-5p as well as the unoccupied orbitals Cs-5d and Li-2p contribute largely to the SHG coefficients of LCPO.

The atomic response theory of NLO material is thought to be a major breakthrough since the development of the anionic group theory.

This new theory reveals the importance of the polarizable atomic orbitals of the occupied and the unoccupied states to the SHG response, which is of scientifically great importance for the understanding of the microscopic mechanism and the functional oriented material design of NLO materials.

 

 

 

The origin for the large SHG effect of LCPO is shown to be the metal-cation-centered groups CsO6 and LiO4 rather than the nonmetal-cation-centered groups PO4. (Image by Prof. DENG’s Group)

 

Contact:

Prof. DENG Shuiquan

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: sdeng@fjirsm.ac.cn

 

 

 

 

 


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