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A. B. A. B. H 2 , He 2 , and HeH. Step 1: A basis for H 2 :. H 2 , He 2 , and HeH (continued). Step 2: Write down the Roothaan-equation. H 2 , He 2 , and HeH (continued). A. B. s. reflection:. H 2 , He 2 , and HeH (continued). A. B. A. B. Step 3: Solve the Roothaan-equation.
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A B A B H2, He2, and HeH Step 1: A basis for H2:
H2, He2, and HeH (continued) Step 2: Write down the Roothaan-equation
H2, He2, and HeH (continued) A B s reflection:
H2, He2, and HeH (continued) A B A B Step 3: Solve the Roothaan-equation
H2, He2, and HeH (continued) A B A B A B Step 3: Solve the Roothaan-equation
H2, He2, and HeH (continued) H H H2
H2, He2, and HeH (continued) energy of electron in lower MO energy of electron in 1sH bond energy: (H2 is stable.) neglect of overlap:
H2, He2, and HeH (continued) central column of an MO-diagram (MO-energy) energy of the whole system (total energy) Intermezzo: MO-diagrams and energy-levels
H2, He2, and HeH (continued) He He2 He
H2, He2, and HeH (continued) energy of electron in lower MO energy of electron in upper MO bond energy: energy of electron in 1sHe (He2 is not stable.) Overlap should not be neglected here.
H2, He2, and HeH (continued) small overlap:
H2, He2, and HeH (continued) He level shifted downwards H level shifted upwards ordering: The average of the levels increases.
H2, He2, and HeH (continued) The lower MO resembles the 1s orbital of He. The upper MO resembles the 1s orbital of H.
H2, He2, and HeH (continued) He HeH H