Question

Rotational motion can also be described as diffusion with a diffusion coeffcient, DR = kBT/6Vn with V the volume and n the viscosity. Assume that the rotational correlation function decays expo- nentially as exp(-6D Rt). What is the rotational diffusion time for a molecule of volume 150X in water (viscosity n = 10-3kg /m.s) at 300K?

Answer 1

The rotational correlation function decays exponentially as given and the part inside exponential gives us the equation of Rotational diffusion time when it is written in the form of rotational time correlation function. This rotational diffusion time is dependent on the Diffusion coefficient which can be calculated easily. The detailed solution is given below:

Ana iffiuaiacaeffeeust Coe 150 A3 where n-viscesity T-teup K Baltemau Coustut J K1 З0 оК .38 X lo-23 13& XIo-23 150 x 1o-30 ALo, Valums V) Ratational loruelation funtion epDet Ratational Correlation time functioA expt ushese Teia Ratational diffstime fut iu. Vn = 1 KeT -3 150 X (0" 138X102 kam 300 K 0.36 X1004ec lo 33 a.76XI023 = 3.6 X 1o : sec Auauex).