We describe a simple model for the melting and optical properties of a DNA/gold nanoparticle aggregate. The aggregate is modeled as a cluster of gold nanoparticles on a periodic lattice connected by DNA bonds, and the extinction coefficient is computed using the discrete dipole approximation. The optical properties at fixed wavelength change dramatically at the melting transition, which is foun...

A method to approximate azimuthally resolved light scattering patterns and phase functions due to diffraction and external reflection by strongly absorbing facetted particles is demonstrated for a cube and compared with results from an exact method, T-matrix. A phase function averaged over a range of orientations of a strongly absorbing hexagonal column of aspect ratio unity has been calculated...

The thermal discrete dipole approximation (T-DDA) is a numerical approach for modeling near-field radiative heat transfer in complex three-dimensional geometries. In this work, the convergence of the T-DDA is investigated by comparison against the exact results for two spheres separated by a vacuum gap. The error associated with the T-DDA is reported for various sphere sizes, refractive indices...

Cirrus clouds play an important role in the Earth’s radiation budget. The transfer of radiation through ice cloud layers depends on the particle phase, concentration, size distribution, and the cloud thickness and shape. Consequently, for reliable simulations of present and future climate using General Circulation Models an accurate representation of ice cloud properties is essential. This give...

The study of scattering and extinction properties of possible nanodiamond grains in the ISM are reported. Calculations using Discrete Dipole Approximation (DDA) for varying ellipsoidal shapes and sizes from 2.5 to 10 nm are considered. Nanodiamonds show negligible extinction from IR to near-UV and very sharp far-UV rise. Comparison with observations rule out possibility of independent nanodiamo...

We present a form of the discrete dipole approximation for electromagnetic scattering computations in time domain. We show that the introduction of complex frequencies, through the Laplace transform, significantly improves the computation time. We also show that the Laplace transform and its inverse can be combined to extract the field inside a scatterer at a real resonance frequency.