Many-electron, many-photon theory of nonlinear polarizabilities

Abstract

We present a many-electron, many-photon (MEMP) nonperturbative theory of nonlinear static and dynamic polarizabilities of polyelectronic atoms and molecules. The time-dependent, dynamic polarization is treated as a frequency-dependent problem with the Floquet assumption that the computed quantities are averaged over a cycle.The MEMP theory defines a non-Hermitian problem whose efficient solution yields a complex eigenvalue to all orders in the interelectronic and the electron ac or dc field interactions. When the real part is subtracted from the unperturbed energy of the free state, we are left with the frequency-dependent total energy shift A(w). This is then fitted to a polynomial expansion whose coefficients are the required polarizabilities representing the induced polarization averaged over a cycle. Results are given for the a, a(w), and y, y(w) of H and of Li-. For Li-, only a had been computed earlier by many-electron approaches. The dynamic a(w) was computed before in a quasi-classical approximation with a simple wave function. Comparison shows a qualitative agreement but not a quantitative one.

Size-consistent approach and density analysis of hyperpolarizability: Second hyperpolarizabilities of polymeric systems with and without defects

“…However, it has been pointed out that qualitative calculations of the hyperpolarizabilities for open-shell systems are very difficult. 50,51 For these systems, the augmentations of the basis set seem to be mandatory. Further, for reasonable treatments of the properties of these systems, we would have to develop the present approach on the basis of the multireference CC ͑MRCC͒ method.…”

Magnitude of static and dynamic polarizabilities of doubly excited states of negative ions: Application to the second bound state ofH−

“…As regards the open channels, for each one we employed a ten-term complex-coordinate Slater-type orbital (STO) representation [5,11]. Given that the frequencies considered ionize the P state with one photon, the following continua were included: 1ses S, 1s ep P, 1sed D, 2ses S, 2sep P, 2sed D, 2pes P, 2pep S, P, D, 2ped, P', D', F'.…”

“…Recently [4,5], we presented a nonperturbative, allorders many-electron, many-photon theory (MEMPT) for the calculation of static as well as dynamic linear and nonlinear polarizabilities. The formalism and its methodology is presented elsewhere [5,11,12], so for reasons of economy its presentation is omitted here.…”

“…The formalism and its methodology is presented elsewhere [5,11,12], so for reasons of economy its presentation is omitted here. Its main features are the following.…”

“…A large number of theoretical methods and results has been published, but most of them refer to the ground state (for a recent list of references see Ref. [5]). …”