Supplementary Information Lone-pair interactions and photodissociation of compressed nitrogen trifluoride D. Kurzydłowski, H. B. Wang, I. A. Troyan, and M. I. Eremets CONTENTS Fig. S 1 Deconvolution of Raman bands observed in phase II at 3.6 GPa. Fig. S 2 Deconvolution of Raman bands observed in phase III at 13.4 GPa. Fig. S 3 Deconvolution of Raman bands observed in phase IV at 32.0 GPa. Fig. S 4 Deconvolution of Raman bands observed in phase IV’ at 47.7 GPa. Fig. S 5 Glowing of the sample during laser heating at 3.2 GPa and comparison of sample before and after heating. Fig. S 6 Relative enthalpy at 0 K per NF3 unit (referenced to that of P212121) of different polymorphs of NF3 Fig. S 7 Comparison of frequencies of Raman active vibrons calculated for Pnma, Pnma-2 and P212121 with experimental Raman shifts. Table S 1 Vibron frequencies (and their symmetries) calculated for Pnma, Pnma-2 and P212121 at 40 GPa. Table S 2 Pressure coefficients (dν/dp) and zero-pressure frequencies (v0) obtained from a linear fit of the pressure dependence of Raman frequencies. Table S 3 Description of various polymorphs of NF3 used in the computational study Cif files of Pnma, Pnma-2, P21/c and P212121 after geometry optimization at 40 GPa. 1 Fig. S 1 Deconvolution of Raman bands observed in phase II at 3.6 GPa. Fig. S 2 Deconvolution of Raman bands observed in phase III at 13.4 GPa. Fig. S 3 Deconvolution of Raman bands observed in phase IV at 32.0 GPa. Fig. S 4 Deconvolution of Raman bands observed in phase IV’ at 47.7 GPa. 2 Fig. S 5 Glowing of the sample during laser heating at 3.2 GPa and comparison of sample before and after heating. Fig. S 6 Relative enthalpy at 0 K per NF3 unit (referenced to that of P212121) of different polymorphs of NF3 3 Frequency calculations performed for the isolated NF3 molecule gave the following vibrational frequencies: ν1 = 998 cm−1, ν3 = 800 cm−1, ν2 = 595 cm−1, and ν4 = 442 cm−1. The obtained frequencies are therefore underestimated by 33, 108, 51 and 55 cm−1 for ν1-4 with respect to experimental values.1 Therefore in order to facilited comparison with experiment in the table and plot below the frequencies of a given vibration manifold (ν1-4) have been shifted by the abovementioned values. Table S 1 Vibron frequencies (and their symmetries) calculated for Pnma, Pnma-2 and P212121 at 40 GPa. Pnma Type of vibration ν1 ν3 ν2 ν4 Pnma-2 P212121 Symmetry* ν (cm-1) Symmetry* ν (cm-1) Symmetry* ν (cm-1) B1u 1100 B2g 1113 A 1057 B3u 1093 B1u 1096 B1 1047 B2g 1091 Ag 1084 B2 1042 Ag 1088 B3u 1082 B1 1022 B1g 1102 B1g 1080 B2 1072 B3g 1014 B1u 999 B3 1069 B3u 1013 B3u 996 B1 1028 B2g 996 Au 995 B3 986 B1u 975 B2g 979 A 983 B2u 956 B2u 945 B2 975 Ag 951 B3g 943 A 921 Au 947 Ag 932 B3 906 B2g 752 B2g 750 A 765 Ag 741 Ag 737 B 750 B1u 735 B3u 724 B2 749 B3u 717 B1u 722 B3 729 B3g 631 B3g 606 B3 623 B2u 600 B1u 603 A 613 B2g 593 B3u 601 B1 591 B3u 585 B2g 592 B2 588 B1g 584 Ag 581 B3 581 B1u 577 Au 579 A 576 Ag 577 B2u 570 B1 555 Au 571 B1g 562 B2 533 * In case of centrsymmetric structures (Pnma, Pnma-2) underlined modes are Raman active, while the remaining ones are IR active. For P212121 all modes are Raman active, while B1, B2, and B3 modes are IR active. 4 Fig. S 7 Comparison of frequencies of Raman active vibrons calculated for Pnma, Pnma-2 and P212121 with experimental Raman shifts. Table S 2 Pressure coefficients (dν/dp) and zero-pressure frequencies (v0) obtained from a linear fit of the pressure dependence of Raman frequencies. Modes of vibration Type of vibration ν1 symmetric stretch ν3 ν2 ν4 asymmetric stretch symmetric bend asymmetric bend ν0 (cm-1) I* dν/dp (cm-1/GPa) III IV IV’ I III IV IV’ 1033 (1032) 1043 1042 1041 3.0 2.4 2.6 2.5 1029 (1025) 1025 1017 1021 2.2 1.9 2.4 2.2 928 (930) 951 954 970 3.5 3.2 3.2 2.6 880 (879) 892 887 894 1.9 2.8 3.2 2.9 872 882 882 2.7 2.5 2.4 862 867 870 2.4 2.4 2.2 658 663 673 2.2 2.5 2.2 661 670 2.1 1.8 505 514 527 3.2 2.8 2.4 506 515 531 1.8 2.3 1.8 501 510 517 1.5 1.7 1.4 2.4 2.5 2.2 650 (645) 496 (494) 2.7 2.8 Mean * values in parentheses are from ref. 1. 5 Table S 3 Description of various polymorphs of NF3 used in the computational study Name Structure Type Space group Z Ref. / Comments Ama2 SbF3 Ama2 4 [2] P212121-2 XeO3 P212121 4 [3] P212121 AsCl3 P212121 4 [2] Pna21 AsF3 Pna21 4 [2] Pnma NCl3 Pnma 4 (12)* [2] Pnma-2 BiF3 Pnma 4 [2] Pnma-3 PBr3 Pnma 4 [2] P63 PI3 P63 2 [2] Rm3 ASI3 Rm3 2 [2] P213 NH3 at high pressure P213 4 [4] Pa–3 NH3 at high pressure Pa–3 8 [5] P21/c-2 NH3 at high pressure P21/c 4 [4] P212121 4 [4] P212121-3 NH3 at high pressure Pc NH3 at high pressure Pc 4 [4] / Original Pma2 symmetry removed P21/c CF4 P21/c 4 [6] / F2 atoms removed *The AsCl3-type structure contains 12 molecules per unit cell, but after geometry optimization we obtained a higher-symmetry cell with Z = 4. Cif files of Pnma, Pnma-2, P21/c and P212121 after geometry optimization at 40 GPa. Pnma: data_findsym-output _audit_creation_method FINDSYM _symmetry_space_group_name_H-M "P 21/n 21/m 21/a" _symmetry_Int_Tables_number 62 _cell_length_a _cell_length_b _cell_length_c _cell_angle_alpha _cell_angle_beta _cell_angle_gamma 5.09279 6.21243 3.92750 90.00000 90.00000 90.00000 loop_ _space_group_symop_id _space_group_symop_operation_xyz 1 x,y,z 2 x+1/2,-y+1/2,-z+1/2 3 -x,y+1/2,-z 4 -x+1/2,-y,z+1/2 5 -x,-y,-z 6 -x+1/2,y+1/2,z+1/2 7 x,-y+1/2,z 8 x+1/2,y,-z+1/2 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy A1 N 4 c -0.01829 0.25000 0.08154 1.00000 B1 F 4 c 0.79411 0.25000 0.83018 1.00000 B2 F 8 d -0.09787 0.07718 0.27499 1.00000 6 Pnma-2: data_findsym-output _audit_creation_method FINDSYM _symmetry_space_group_name_H-M "P 21/n 21/m 21/a" _symmetry_Int_Tables_number 62 _cell_length_a _cell_length_b _cell_length_c _cell_angle_alpha _cell_angle_beta _cell_angle_gamma 5.15959 6.21077 3.83750 90.00000 90.00000 90.00000 loop_ _space_group_symop_id _space_group_symop_operation_xyz 1 x,y,z 2 x+1/2,-y+1/2,-z+1/2 3 -x,y+1/2,-z 4 -x+1/2,-y,z+1/2 5 -x,-y,-z 6 -x+1/2,y+1/2,z+1/2 7 x,-y+1/2,z 8 x+1/2,y,-z+1/2 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy A1 N 4 c 0.27724 0.25000 0.89293 1.00000 B1 F 4 c -0.02831 0.25000 0.36364 1.00000 B2 F 8 d 0.65248 0.57806 0.31377 1.00000 P21/c: data_findsym-output _audit_creation_method FINDSYM _symmetry_space_group_name_H-M "P 1 21/c 1" _symmetry_Int_Tables_number 14 _cell_length_a _cell_length_b _cell_length_c _cell_angle_alpha _cell_angle_beta _cell_angle_gamma 6.70307 3.89499 5.11746 90.00000 112.29487 90.00000 loop_ _space_group_symop_id _space_group_symop_operation_xyz 1 x,y,z 2 -x,y+1/2,-z+1/2 3 -x,-y,-z 4 x,-y+1/2,z+1/2 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy A1 N 4 e 0.74860 0.40695 0.64799 B1 F 4 e 0.56963 0.22617 0.63938 B2 F 4 e -0.08589 0.18775 0.79795 B3 F 4 e 0.76161 0.65077 0.84720 1.00000 1.00000 1.00000 1.00000 7 P212121: data_findsym-output _audit_creation_method FINDSYM _symmetry_space_group_name_H-M "P 21 21 21" _symmetry_Int_Tables_number 19 _cell_length_a _cell_length_b _cell_length_c _cell_angle_alpha _cell_angle_beta _cell_angle_gamma 6.09666 7.25738 2.77297 90.00000 90.00000 90.00000 loop_ _space_group_symop_id _space_group_symop_operation_xyz 1 x,y,z 2 x+1/2,-y+1/2,-z 3 -x,y+1/2,-z+1/2 4 -x+1/2,-y,z+1/2 loop_ _atom_site_label _atom_site_type_symbol _atom_site_symmetry_multiplicity _atom_site_Wyckoff_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy A1 N 4 a 0.29932 0.29046 -0.04332 B1 F 4 a 0.29297 0.12088 0.73296 B2 F 4 a 0.12795 0.38342 0.73259 B3 F 4 a 0.47758 0.36985 0.73878 1.00000 1.00000 1.00000 1.00000 References 1 M. Gilbert, P. Nectoux, and M. Drifford, J. Chem. Phys. 68, 679 (1978). 2 J. Galy and R. Enjalbert, J. Solid State Chem. 44, 1 (1982). 3 D. H. Templeton, A. Zalkin, J. D. Forrester, and S. M. Williamson, J. Am. Chem. Soc. 85, 817 (1963). 4 C. J. Pickard and R. J. Needs, Nat. Mater. 7, 775 (2008). 5 G. I. G. Griffiths, R. J. Needs, and C. J. Pickard, Phys. Rev. B 86, 144102 (2012). 6 Y. A. Sataty, J. Chem. Phys. 62, 1094 (1975). 8