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Table 2 PCA on the anion or anion group in the outermost layer of a molecular cluster

From: Improved volume variable cluster model method for crystal-lattice optimization: effect on isotope fractionation factor

Cluster

Molecular formula

Total valence

1 × 

2 × 

5 × 

Net charge

   

a1 × 

b1 × 

a2 × 

b2 × 

c2 × 

a5 × 

b5 × 

 

Si–Qtz

Si24O66

 − 36

180 × (4/4) × 1/5

0

O–Qtz

Si29O77

 − 38

190 × (4/4) × 1/5

0

Zn–Al LDH

Zn13Al3O60C4H30

 − 39

12 × 3/6

90 × (1 + 3/6 + 2/6) × 1/5

0

Cd–Cal

Ca6Cd(CO3)26

 − 38

60 × 2/6 × 1/2

210 × (2/6 + 2/6) × 1/5

0

Cd–HAp

Ca12Cd(PO4)30(OH)3

 − 67

2 × 2/7

10 × 2/9

24 × (2/9 + 2/9) × 1/2

16 × (2/7 + 2/7) × 1/2

40 × (2/7 + 2/9) × 1/2

150 × (2 × 2/9 + 2/7) × 1/5

140 × (2 × 2/7 + 2/9) × 1/5

0

  1. The outermost layer of the Si–Qtz molecular cluster has 5 × point charges (180). The outermost layer of the O–Qtz molecular cluster has 5 × point charges (190). The outermost layer of the Zn–Al LDH molecular cluster has 1 × point charges (12) and 5 × point charges (90). The outermost layer of the Cd–Cal molecular cluster has 2 × point charges (60) and 5 × point charges (210). The outermost layer of the HAp molecular cluster has a1 × (2), b1 × (10), a2 × (24), b2 × (16), c2 × (40), a5 × (150), and b5 × (140) point charges
  2. Si–Qtz net charge (0) = total cluster valent (-36) + total point charge (+ 36). O–Qtz net charge (0) = total cluster valent (-38) + total point charge (+ 38). Zn–Al LDH net charge (0) = total cluster valent (-39) + total point charge (+ 39). Cd–Cal net charge (0) = total cluster valent (-38) + total charge of point charge (+ 38). Cd–HAp net charge (0) = total cluster valent (-67) + total charge of point charge (+ 67)