Study of linear and nonlinear optical properties of dendrimersusing density matrix renormalization group method

摘要

We have used the density matrix renormalization group (DMRG) method to study the linear andnonlinear optical responses of first generation nitrogen based dendrimers with donor acceptorgroups. We have employed Pariser–Parr–Pople Hamiltonian to model the interacting πelectrons inthese systems. Within the DMRG method we have used an innovative scheme to target excitedstates with large transition dipole to the ground state. This method reproduces exact optical gaps andpolarization in systems where exact diagonalization of the Hamiltonian is possible. We have used acorrection vector method which tacitly takes into account the contribution of all excited states, toobtain the ground. state polarizibility, first hyperpolarizibility, and two photon absorption crosssections. We find that the lowest optical excitations as well as the lowest excited triplet states arelocalized. It is interesting to note that the first hyperpolarizibility saturates more rapidly with systemsize compared to linear polarizibility unlike that of linear polyenes.