Simulated pressure-induced blue-shift of phase-matching region and nonlinear optical mechanism for K3B6O10X (X=Cl,Br) Bingbing Zhang(张兵兵),1,2 Ming-Hsien Lee(李明憲),1,3 Zhihua Yang(杨志 华),1,a) Qun Jing(井群) 1, Shilie Pan(潘世烈),1,a) Min Zhang(张敏),1 Hongping Wu(吴红萍), 1 Xin Su(苏欣),1,2 and Cheng-Shun Li(李政勛)3 1Key Laboratory of Functional Materials and Devices for Special Environments of CAS; Xinjiang Key Laboratory of Electronic Information Materials and Devices; Xinjiang Technical Institute of Physics & Chemistry of CAS, 40-1 South Beijing Road, Urumqi 830011, China. 2University of Chinese Academy of Sciences, Beijing 100049, China; 3Department a) of Physics, Tamkang University, New Taipei City 25137, Taiwan Electronic mail: zhyang@ms.xjb.ac.cn (Zhihua Yang); slpan@ms.xjb.ac.cn (Shilie Pan) The expression of Two-Band (TB) processes in the equation given by Lin et al.1 is (TwoBands)= Im[ pvc pcv ( pvv pcc )] e3 d 3k . (1) P ( ) 2 3 m vc 4 3 vc5 Where, α, β, γ are Cartesian components, v and v′ denote valence bands, c and c′ refer to conduction bands, and P(αβγ) denotes full permutation. The band energy difference and momentum matrix elements are denoted as ℏωij and Pijα, respectively. In Equation (1), Im[ pvc pcv ( pvv pcc )] i { pvc pcv ( pvv pcc ) [ pvc pcv ( pvv pcc )]*} . 2 * For (pvc)=pcv , and pvc imvc rvc , Im[ pvc pcv ( pvv pcc )] i [imvc rvc imcv rcv mvc imcv rcv imvc rvc mvc ] 2 im3 (vc cv )(rvc rcv vc rcv rvc vc ) 2 pcc mvc , the equation (1) Where pvv (TwoBands)= (TwoBands)= ie3 2 2 ie3 2 2 ie3 2 2 ( ) d 3k P( )[ vc 5 cv (rvc rcv vc rcv rvc vc )] (2) 3 4 vc vc d 3k 1 P ( )[rvc rcv vc rcv rvc cv ] 3 3 4 vc vc d 3k 1 [(rvc rcv vc rvc rcv vc rvc rcv vc rvc rcv vc rvc rcv vc rvc rcv vc ) 3 3 4 vc vc (rcv rvc cv rcv rvc cv rcv rvc cv rcv rvc cv rcv rvc cv rcv rvc cv )] ie3 2 2 d 3k 1 [(rvc rcv (vc cv ) rvc rcv( vc + cv ) rvc rcv( vc +cv) 3 3 4 vc vc rvc rcv ( vc +cv) rvc rcv( vc + cv ) rvc rcv( vc +cv )] =0 For determining the cutting radius of specific ion, we investigated the charge-density distribution of KBOC and KBOB. The charge-distribution of the B 6O10 unit is relatively nonlocal due to the covalent properties of B-O bonding. While the charge-distribution of Cl, Br and K is spherelike that show more ionic properties. Therefore, the B 6O10 units are treated as a whole, Cl, Br and K cut as an isolated atom. We first determine the cutting radius of K and O by searching the minimum points of charge density between K and the nearest O. Thus, the cutting radius of K and O is 1.308 and 1.370 Å, respectively. Considering the nonlocal charge-distribution of B6O10, the cutting radius of B is set to the covalent radius (0.82 Å) in order to cover the nonlocal electrons. The cutting radius of Cl and Br is set as 1.468 Å. The contribution of an ion or an ion group is extracted by indirect stratage, i.e., the contribution of ion A is obtained by substracting the χ(2) contribution of other ions except A from the origin χ(2) value, that is, χ(2)(A) = χ(2)(origin) − χ(2)(cut A). Figure S1. The calculated polarizabilities α∕∕ and α┴ of (B6O13)−2 group in free and under 10 GPa z-direction pressure, respectively. Table SI. Sellmeier coefficients derived from the measured and calculated refractive indices. Sellmeier equation: n A B F2 C Crystal n A B C F no 2.47524 0.01450 0.01667 -0.01249 ne 2.33147 0.01264 0.01634 -0.00879 no 2.58462 0.01574 0.01865 -0.00125 ne 2.43277 0.01298 0.01802 -0.00120 no 2.49322 0.01325 0.01589 -0.00068 ne 2.34857 0.01091 0.01510 -0.00063 no 2.69556 0.01565 0.01808 -0.00134 ne 2.42929 0.01090 0.01627 -0.00119 no 2.63985 0.01370 0.01453 -0.00058 ne 2.45767 0.01080 0.01330 -0.00050 KBOB Exp. Cal. KBOC Cal. free z-pressure h-pressure 2 Reference 1. Lin, J.; Lee, M.-H.; Liu, Z.-P.; Chen, C.; Pickard, C. J. Mechanism for linear and nonlinear optical effects in β-BaB3O4 crystals. Phys. Rev. B 1999, 60 (19), 13380-13389.