4

Sn      0.149777555970285      0.093644321539677      0.273541036547340
Na      1.532739635050214      1.522409891693018     -0.104007624175541
Na      1.794978828798281     -0.011851384255832      1.478310137232264
Sn      0.291192563847456      1.306912291017673      1.661889860222413