December 7, 2016

Can Quantized Vibrational Effects be Obtained from Ehrenfest Mixed Quantum-Classical Dynamics?

An interesting question is whether or not mean-field or “Ehrenfest” mixed quantum-classical dynamics can capture the quantized vibrational features in photoabsorption spectra that result from infrared and Raman-active vibrational transitions. We show that vibrational and electronic absorption spectra can be obtained together within a single Ehrenfest simulation. The electronic transitions show new sidebands that are […]

November 1, 2016

Ab Initio Transient Vibrational Spectral Analysis

Pump probe spectroscopy techniques have enabled the direct observation of a variety of transient molecular species in both ground and excited electronic states. Time-resolved vibrational spectroscopy is becoming an indispensable tool for investigating photoinduced nuclear dynamics of chemical systems of all kinds. We developed a transient vibrational analysis protocol combining ab initio direct molecular dynamics […]

October 6, 2016

Relativistic Two-Component Particle–Particle TDA

In essence, this work discusses a simple scheme to compute the fine–structure splittings (FSS) of molecules using the pp-TDA. From the converged wave function of the (+2) cation of molecular systems, the neutral excitation energies may be recovered via the pp-TDA. If the cation was converged using a relativistic Hamiltonian, orbitals with total angular momentum […]

September 26, 2016

Shine On You Crazy Diamond

The group has used its experience in modeling doped nanoclusters to tackle the challenge of predicting the optical properties of nitrogen-vacancy (NV) color centers in quantum-confined nanodiamonds. As NV-containing diamonds approache the nanosize (d≈5 nm), they show promise for many technological applications, such as quantum computing, ultra-sensitive magnetometry, and bio-labeling. Doping may introduce new sub-band […]

September 15, 2016

Real-time Exact Two-Component Theory

We recently extended electronic dynamics to include relativistic effects, such as spin-orbit coupling. These effects are critical when investigating heavy elements and spin phenomena in chemistry. Using our new method, we showed how you can easily obtain the full absorption spectrum for molecules and atoms that includes otherwise spin-forbidden processes. Non-relativistic theories cannot capture these […]