Electron correlations in narrow energy bands. II. The degenerate band case

摘要: In a previous paper theory of correlation effects in narrow s -bands was described. this generalization that applicable to degenerate electron bands is developed. The based upon the notion case most important correlations are those between electrons on same atom. solution obtained has property going over into ordinary band appropriate limit (no interaction) and exact atomic (Heitler-London) opposite (zero band-width). order elucidate general properties some simplified models discussed, more elementary implications when applied d transition metals indicated. A physical interpretation results given; picture which emerges found be closely related discussed earlier by Van Vleck.