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Optical anisotropy of synthetic polynucleotides. II. Calculation of π‐electron polarizability of uracil and adenine
Author(s) -
Takashima Shiro
Publication year - 1969
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1969.360080207
Subject(s) - polarizability , chemistry , uracil , anisotropy , electron , eigenvalues and eigenvectors , computational chemistry , molecule , molecular physics , quantum mechanics , physics , organic chemistry , dna , biochemistry
The π‐electron polarizability of conjugated base molecules such as uracil and adenine are calculated semiempirically by using molecular orbital theories. The Hüekel method and the self‐consistent‐field (SCF) theory are used in the present calculation. The theoretical values obtained by the Hüekel method are consistently larger than the experimental results. The values obtained by the SCF theory are in good agreement with observed values. It is clearly demonstrated that the SCF method is better than the Hükel method for the calculation of polarizability. The polarizability of the adenine–uracil pair is calculated as the sum of the polarizabilities of adenine and uracil and also calculated by solving the eigenvalue problem for the A–U pair as an entity. The second method gives considerably larger polarizability than the first method. Discussions are presented and it is demonstrated that the second method is the correct way to calculate the polarizability of the A–U pair.