158 a Lecture 23 H2 Valence Bond Theory

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158 a Lecture 23 H2 Valence Bond Theory
Extensions Simple MO of Homonuclear Diatomics

• Extensions to get better energies
• Computer Calculations (Spartan and
  Gaussian)
• Qualitative Modeling via Simple MO
• Guiding Principles
• Do H2 MOs from AOs
• Apply to homonuclear diatomics
• Fred J. Grieman

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H2 Results

• E E1s (J K)/(1S)
• K responsible for bonding
  anti-bonding
• (w.f. overlap nucleus
  interaction)
• E bonding Eb / E- anti-bonding Ea
• ? (2 2S)1/2 (1sA 1sB) ?
• ?b?b 1/(22S) 1sA2 1sB2 2(1sA1sB)
• 
  
  Constructive Interference
• ?a?a 1/(2-2S) 1sA2 1sB2 - 2(1sA1sB)
• 
  
  Destructive Interference
• 
  
  Nodal Plane at Center

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H2 Molecule via MO-LCAO
?b ? (1sA 1sB) with spin!
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H2 Molecule via MO-LCAO
?b(1) ?b(2) ? (1sA(1)(1sB(1) (1sA(2)(1sB(2)
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Qualitative Modeling via Simple MO Guiding
Principles then do H2 MOs from AOs
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