Computation of Dissociation Energies of Diatomic Molecules K. Ramani and A. M. Ghodgaonkar, Western Regional Instrumentation Centre. University of Bombay, Bombay 400 098 India An accurate knowledge of dissociation energies of diatomic molecules is of fundamental importance in molecular spectroscopy. Usually the dissociation energy D. is determined by knuwledge of either uf the following: la) Potential Kunctim
No.
Molecule
k = 0.18 tor 0.5
lbl Plnt of (A(;12versns a (el Bond energies.
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Each method has its own merits and demerits. Potential Iunct~on\are empiricdi u.i~l:ill\and differ widrly in I hrir forms ( I :{I with the t ~ s e,dsev~.ri~l sp~.vtroscol~ic c g m < t i l n t i The [Ir vnlllrs m!#~hh?inrd IIV pro1n.r hhiwior 01 (he pnlenlial a1 large v;dw* ot'intrrnudear dist;arwe and are inarcurare IIV l(F4 w ~ t h the observed values. The accuracy of D, values depends to a large extent on the rate of convergence and region of ctmvergence. On the other hand, a plot of (A(;)' versus u gives the crudest estimation of 11, values (41, where 0 = W." - w,x.v2
(11
and where u is the vihrational auantum number and o.... o,X. - . are the spectroscopic constants. The difficulty experienced in this method lies in the extrapolation of the curve as (A(;)' is obtained for smaller values of the vihrational quantum numher u. Comwuted values hv this method are off hv as much as 36%. In view of the merits and demerits enumerated above, we energ! considered it u.cmhwhile I,, wrrt.late thr di.;sw~ati#m d t h v d~itr~nnic molrn~lrswith the dwocia[i
