Page 187 - Valence Bond Methods. Theory and Applications

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Tablà 12.9.BF: The most important terms ił the wave functioł wheł hybrid
AOs are used as determined by the magnitudes of the coefficientsŁ Results for
standard tableaux and HLSP functions are the same.
2
1 12 Second row heteronuclear diatomics 4
3
Num. 1 1 2 2
       
h oa h oa h oa h oa h oa h oa h ob h ob
STF  h ob h ob   h ob h ob   h ob h ob   h ib h ib 
or  2p xb   h ib   h ib   2p yb 




 2p yb
 2p xb
 h ib
 h ib
HLSP  2p yb 2p yb   2p xb 2p xb   2p yb 2p yb   h oa h ia 
h ia h ib 2p yb 2p yb 2p xa 2p xb 2p xa 2p xb
st f
C (mił ) 0.335 49 0.260 92 0.228 79 0.160 75
i
hlsp
C (mił ) 0.335 49 0.260 92 0.228 79 0.147 62
i
Tablà 12.10.BF: EGSO weights (standard tableaux functions) for spherical
AOs, upper group, and hybrid AOs, lower groupŁ These are weights
for whole symmetry functionsŁ
1 2 3 4
Num. 2 1 1 2
       
2s a 2s a 2s a 2s a 2s b 2s b 2s b 2s b
 2s b 2s b   2s b 2s b   2p zb 2p zb   2p zb 2p zb 
STF  2p zb   2p xb   2p xb   2p yb 




 2p zb
 2p yb
 2p xb
 2p xb
2p yb 2p yb 2p yb 2p yb 2p yb 2p yb 2s a 2p za
       
2p xa 2p xb 2p za 2p zb 2s a 2p za 2p xa 2p xb
Wt 0.464 83 0.302 50 0.08‚ 13 0.028 11
Num. 1 2 2 1
       
h oa h oa h oa h oa h ob h ob h ob h ob
 h ob h ob   h ob h ob   h ib h ib   h ia h ia 
STF  2p xb   h ib   2p yb   2p xb 




 2p yb
 2p xb
 2p xb
 h ib
2p yb 2p yb 2p yb 2p yb h oa h ia 2p yb 2p yb
       
h ia h ib 2p xa 2p xb 2p xa 2p xb h oa h ib
Wt 0.486 57 0.25‚ 67 0.078 54 0.036 12
Thà EGSO weights shðwł ił Tablà 12.10 for thà two orbital arrangements display
ał interesting switch. For thà spherical AOs a cylindrically averaged π bond is thà
principal configuration and thàσ bond is thà second one. Thà hybri AOs shðw thà
opposità order with thàσ bond structure relatively more strongly favored thał ił
thà spherical case. In both cases there is considerablà competition between thà two
bond types, and thà VBprediction is that thày are strongly mixed ił thà molecule.
We defer a discussion of thà dipolà moment until later.