Spin projections for even electron systems

A new method is presented for obtaining the spin eigenfunctions of 2n electron systems in the spin state S and M_S = 0. Using a modified Young operator the function for the state S, M_S ( = S) of the system is first projected out. The projected function is then symmetrized over the last n particles and the weight lowering operator ? is then applied to it, resulting in a projection of the state S, 0. To within a multiplicative factor, the resulting function is identical with the one resulting from the vector coupling methods.     

A new program for CI calculations in molecules

Based on the formalism developed in a recent note, we have worked out a program for CI calculations in molecules. In the present note, the details of the program are discussed. The usefulness of the program has been illustrated using some calculations. On leave from the Indian Institute of Technology, Bombay, India.     

Selective control of HOD photodissociation using low quanta O–D excitation and field optimized initial state (FOIST) based combination of states and colors

Selective Control of HOD photodissociation has been investigated using simple field profiles. Initial results indicate that preferential dissociation of O–H bond may be achieved from the ground vibrational state and that the O–D bond can be selectively dissociated using only the fundamental excitation in this mode. Dissociation from 2 quanta of excitation in the O–D mode produces 82.8% products with O–D bond dissociation. Preferential maximization of O–D dissociation vis-à-vis O–H bond may also be achieved from the ground vibrational state using a combination of two lasers with carrier frequencies 54920 cm⁻¹ and 52203 cm⁻¹. The use of Field Optimized Initial STate (FOIST) based scheme to enhance selective control of HOD photodissociation provides additional 6 − 8% H–O + D products compared to those obtained without FOIST.