Table 2 Calculated and experimental lowest energy optical transitions in As and Sb iii and v sulfide monomers and dimers (TD B3LYP results in italics, CIS oscillator strengths in parentheses)

AsS₃^3-···4H₂0

6-311 +G(2d,p)

2.7

4.0

6-311G(2d,p)

4.1

4.4

SBK+As, S, O d

4.3

4.5

As(SH)₃···4H₂0

6-311+G(2d,p)

5.3

5.3

AsS₄^3-··· 6H₂O

6-311+G(2d,p)

4.0

4.6

6-311G(2d,p)

4.1

4.7

SBK+As, S, O d

4.6

4.7

SbS₃^3-···4H₂0

SBK+Sb, S, 0 d

4.3

4.5

SbS₄^3-··· 6H₂0

SBK+Sb, S, 0 d

4.7

4.8^a

4.35

3.3

Sb₂S₄^2-···4H₂O

3.2 (0)

SBK+Sb, S, O d

4.0 (0)

4.5 (0.074)

Sb₂S₅^2-··· 5H₂O

4.1 (0.030)

SBK+Sb, S, O d

4.6 (0.028)

Sb₂S₆^2-··· 6H₂0

SBK+Sb, S, 0 d

4.6

4.7 (0.022)

As(S₄)(SH)

6-311+G(2d,p)

4.0

4.1