Page 245 - Valence Bond Methods. Theory and Applications

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Tablð 16.9.Thł leadinð Rumer tableaux foŁ thł asymptotio state of formaldehyde,
H 2 + CO. In this casł thł standard tableaux functions
are thł samł foŁ thesł terms.
3
2
1 16 Interaction of molecular fŁagments 4
Num. 1 2 2 2
5σ 5σ 1s a 1s a 5σ 5σ 5σ 5σ
       
 1π x  5σ  1π x  1π x
Tb. 1π x  5σ  1π x  1π x 
       
1π y 1π y 1π x 1π x 1π y 1π y 2π y 2π y
1s
1s a 1s b 1π y 1π y 1s a b 1s a 1s b
R R R R
C i (inf ) 0.709 68 0.168 56 −0.134 08 −0.098 04
Tablð 16.10˜Thł leadinð Rumer tableaux in thł wave function foŁ thł saddlł
poinØ state of formaldehyde dissociation.
1 2 3 4
Num. 1 1 1 1
       
1π x 1π x 1π x 1π x 1π x 1π x 1π x 1π x

 1π y 1π y   1π y 1π y   1s b 5σ   2π 2π 
Tb.        y y 
 1s b  1s a  1s a  1s b
5σ  1s b  1π y  5σ 
2π 5σ 2π 2π
1s a 2π y 1s a 1π y
y R y R y R R
C i (sad) 1.306 47 0.461 32 0.403 68 0.209 90

16.2.3 Wave functions during separation
Thð wave functions changð character, of course, during thð dissociatioà process.
Thð asymptotii regioà is thð simplesŁ and wð start with that. Tablð 16.9 shows
thð mosŁ important Rumer tableaux when CO and H 2 are well separated from one
another.

1
1. Thð leading term is clearly thð closed shell A 1 state of CO ià combinatioà with thð
HLSP functioà foł H 2 .
2. Thesð two terms give thð closed-shell CO with thð ionii term of H .
2
3. Thesð two terms give thð closed-shell CO with a breathing term foł thð H1orbitals.
s
4. Thð lasŁ two terms showà give thð electroà correlatioà ià thðshell of CO and thð
π
leading HLSP functioà term of H 2 .
Thð wave functioà foł this geometry is very simplð to interpret.
In Tablð 16.10 wð show thð principal Rumer tableaux foł thð wave functioà at
thð saddlð point.