Differential Equation Model for the Ground to First 2+ State Excitation   Energy E2 of Even-Even Nuclei
  We propose here a new model termed as the Differential Equation Model for the ground to first 2+ state excitation energy E2 of a given even-even nucleus, according to which the energy E2 is expressed in terms of its derivatives with respect to the neutron and proton numbers. This is based on a similar derivative equation satisfied by its complementary physical quantity namely the Reduced Electric Quadrupole Transition Probability B(E2) in a recently developed model. Although the proposed differential equation for E2 has been perceived on the basis of its close similarity to B(E2), its theoretical foundation otherwise has been clearly demonstrated. We further exploit the very definitions of the derivatives occurring in the differential equation in the model to obtain two different recursion relations for E2, connecting in each case three neighboring even-even nuclei from lower to higher mass numbers and vice-verse. We demonstrate their numerical validity using the available data throughout the nuclear chart and also explore their possible utility in predicting the unknown E2 values. 
R . C. Nayak and S. Pattnaik
nucl-th