A QM/MM and QM/QM/MM study of Kerr, Cotton--Mouton and Jones linear birefringences in liquid acetonitrile

• QM/MM and QM/QM/MM protocols are applied to the ab initio study of the three linear bire-fringences Kerr, Cotton–Mouton, and Jones, as shown by acetonitrile in the gas and pureliquid phases. The relevant first-order properties as well as linear, quadratic, and cubicfrequency-dependent response functions were computed using time-dependent Kohn–Shamdensity-functional theory with use of the standard CAM-B3LYP functional. In the liquid phase,a series of room temperature (293.15 K) molecular dynamics snapshots were selected, for whichaveraged values of the observables were obtained at an optical wavelength of 632.8 nm. Thebirefringences were computed for electric and magnetic induction fields corresponding to the lab-oratory setup previously employed by Roth and Rikken in Phys. Rev. Lett. 85, 4478, (2000).Under these conditions, acetonitrile is shown to exhibit a weak Jones response — in fact roughly6.5 times smaller than the limit of detection of the apparatus employed in the measurementsmentioned above. A comparison is made with the corresponding gas-phase results and an as-sessment is made of the index of measureability, estimating the degree of overlap of the threebirefringences in actual measurements. For acetonitrile, it is shown that this index is a factorof 3.6 and 6.7 larger than that of methylcyclopentadienyl-Mn-tricarbonyl and cyclohexadienyl-Fe-tricarbonyl, respectively — two compounds reported in Phys. Rev. Lett. 85, 4478, (2000) to exhibita strong Jones signal.

Subject headings

NATURVETENSKAP  -- Kemi -- Teoretisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Theoretical Chemistry (hsv//eng)

Keyword

Linear birefringence

Jones

Kerr

Cotton--Mouton

QM/MM

QM/QM/MM

PE

PDE

Teoretisk kemi och biologi

Theoretical Chemistry and Biology

Teoretisk kemi och biologi

Theoretical Chemistry and Biology

Publication and Content Type

ref (subject category)

art (subject category)