A Double Hard Sphere Model of Liquid Semi-Metals: Applications to Bismuth and Tin

T h e d o u b l e hard sphere m o d e l prev ious ly used t o calculate the interference f u n c t i o n s for l iquid G e , S b a n d G a has n o w been appl ied t o S n a n d Bi . T h e m a i n features of the observed interference funct ions just a b o v e t h e mel t ing points h a v e been reproduced , within e x p e r i m e n t a l error, b y the superposit ion o f t w o different partial interference funct ions represented b y hard sphere f u n c t i o n s with packing densities o f 0 . 4 7 5 a n d 0 . 4 7 0 for S n a n d 0 . 4 3 0 a n d 0 . 4 0 0 for Bi a n d respect ive hard sphere d i a m e t e r s ; 3 . 0 3 0 A a n d 2 . 4 2 0 A : 3 . 3 3 5 A a n d 2 . 4 5 0 A . T h e m o d e l has been deve loped to g ive a qual i ta t ive picture of the bonding in the liquid w i t h t h e short distance associated with possible o v e r l a p o f p orbitals . F u r t h e r , this m o d e l has been shown to be in keeping w i t h an a l ternat ive e m p l o y i n g a ledge t y p e interatomic potential b y referring to the measured compressibilities.