Evolutionary search for BiInS 3 crystal structure and predicting its second-order nonlinear optical property Chen-sheng Lin a , Wen-dan Cheng a,n , Zhong-zhen Luo a,b , Guo-liang Chai a,b a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Mater, the Chinese Academy of Sciences, Fuzhou, Fujian 350002, China b Graduate School of the Chinese Academy of Sciences, Beijing 100039, PR China article info Article history: Received 14 September 2012 Received in revised form 4 December 2012 Accepted 9 December 2012 Available online 14 December 2012 Keywords: Crystal structure prediction Nonlinear optical property BiInS 3 Density functional theory abstract We used ab initio evolutionary algorithm to predict the stable and energetically competitive metastable structures of the nonlinear optical materials BiInS 3 crystal. The powerful evolutionary algorithm allows us to find the global minimum of the energy landscape with dramatic reduced candidate numbers. Combining geometry optimization with density functional method and the phonon dispersion calculation it is possible for us to determine the stable structure of BiInS 3 within only several tens of thousand candidates. The proposed most stable structure adopts the P2 1 space group, and its second- harmonic generation coefficient is as large as 59 pm/v. The former synthesized BiInS 3 is probable corresponding to the metastable Pnma structure. The existence of iso-energy structures at the metastable energy range suggests that more delicate synthetic method is required to obtain high quality BiInS 3 crystal. & 2012 Elsevier Inc. All rights reserved. 1. Introduction Nonlinear optical wavelength conversion of infrared laser is a widely used technique in the near-infrared or mid-infrared (mid-IR) laser application. These conversions acquired the second-order nonlinearity behavior of non-centrosymmetric infrared nonlinear material. The currently used mid-infrared nonlinear optical (NLO) crystals are mainly ternary compound like ZnGeP 2 , AgGaS 2 and LiInS 2 [1–3]. However, none of these materials could meet all the demand of practical requirements such as high laser damage threshold, low absorption loss, wide transparent wave rang, low thermal lensing and non-critical phase matching. Thus, the search- ing for new infrared materials with better required properties is undertaken. Recently, the Bi–In–S ternary system was reexamined due to the building unit Bi–S and In–S play an important role in the IR nonlinear optical materials like LiInS 2 , La 4 InSbS 9 , and Ba 2 BiInS 5 [3–5]. It is expected that the combination of stereochemical activity 6s 2 lone pair of Bi atom and the distorted InS 4 tetrahedron would produce promising nonlinear optical active materials [6]. Up today, five Bi–In–S ternary compounds were synthesized and four of them had been determined their crystal structures. Bi 14.7 In 11.3 S 38 , Bi 2 In 4 S 9 and Bi 3 In 5 S 12 crystallized in the centrosymmetric monoclinic P2 1 /m, P2 1 /m and C2/m space group, respectively [6–8]. The latest synthe- sized compound Bi 3 In 4 S 10 adopted the non-centrosymmetric space group Pm [6]. Interestingly, the minimum chemical composition ratio 1:1:3 of Bi–In–S system with the formula BiInS 3 had early been synthesized but its crystal structure could not been determined with enough precise [9]. All the synthesized Bi–In–S crystal were grown from the reactant Bi 2 S 3 and In 2 S 3 with different chemical ratio near their melting points and then anneal to crystallized temperature for some times. Depending on special reaction condition, different crystals with varied chemical composition were obtained. Bi 2 In 4 S 9 and Bi 3 In 5 S 12 were synthesized by using chlorine as transport agent [7,8]. Single crystal BiInS 3 could not obtained by this chemical vapor transport method because of the predominant formation of sulphide halides. Bi 14.7 In 11.3 S 38 and Bi 3 In 4 S 10 were synthesized via a two-step flux technique using the KBr as the fluxer to grow the single crystals [6]. Although a molar ratio 1:1 of Bi 2 S 3 and In 2 S 3 was used in this reaction, it turned out to crystallize in compound as formula Bi 14.7 In 11.3 S 38 . Thus the method to grow good quality crystal and its electronic properties of BiInS 3 is still an open question. The known ternary Bi–In–S crystal structures show complicated In–S and Bi–S polyhedron packing style. It shows that the bonding picture of Bi–In–S has tremendous possibilities. It is hard to predict the BiInS 3 crystal structure based on the other composition ternary Bi–In–S compounds. In fact, the crystal structure prediction was believed to be an ‘impossible’ task such as the stock market, earth- quakes, not steady (or abrupt) process in the past [10]. However, this situation was changed since the beginning of this century, when the ab initio evolutionary crystal structure prediction methods like USPEX code (Universal Structure Prediction: Evolutionary Xtallography) was developed [11, 12]. USPEX combined the local minimization method and the evolutionary algorithms to systemically predict the most Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jssc Journal of Solid State Chemistry 0022-4596/$ - see front matter & 2012 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jssc.2012.12.011 n Corresponding author. Fax.: þ86 591 8371 4946. E-mail address: cwd@fjirsm.ac.cn (W.-d. Cheng). Journal of Solid State Chemistry 199 (2013) 78–83