THEORETICAL TREATMENT OF THE ELECTRONIC CIRCULAR-DICHROISM SPECTRUM AND THE OPTICAL-ROTATORY POWER OF H2S2

The electronic circular dichroism spectrum and the optical rotatory po wer of dihydrogen disulfide are investigated at CI ab initio level. Th e calculation of the optical rotatory power is performed by a variatio n-perturbation method including electronic correlation and ensuring ga uge invariance. Application to dihydrogen disulfide shows that its opt ical rotatory power is weak and is essentially due to the first lowest spectroscopic states. Moreover, the correlation between the optical r otatory power and the conformation of the molecule is studied and show s the importance of the lone pairs of sulphur atoms in the optical pro perties of the disulfide compounds. The investigation of the optical r otatory power as a function of the wavelength of incident light enable s us to recover the experimental law of Biot, and its sign agrees well with experimental data on compounds of the same family (R2S2). (C) 19 98 Elsevier Science B.V.