Contact

Additional Info

  • Mail Code: 5080

All Publications

  • Prediction of photodynamics of 200 nm excited cyclobutanone with linear response electronic structure and ab initio multiple spawning. The Journal of chemical physics Hait, D., Lahana, D., Fajen, O. J., Paz, A. S., Unzueta, P. A., Rana, B., Lu, L., Wang, Y., Kjønstad, E. F., Koch, H., Martínez, T. J. 2024; 160 (24)

    Abstract

    Simulations of photochemical reaction dynamics have been a challenge to the theoretical chemistry community for some time. In an effort to determine the predictive character of current approaches, we predict the results of an upcoming ultrafast diffraction experiment on the photodynamics of cyclobutanone after excitation to the lowest lying Rydberg state (S2). A picosecond of nonadiabatic dynamics is described with ab initio multiple spawning. We use both time dependent density functional theory (TDDFT) and equation-of-motion coupled cluster singles and doubles (EOM-CCSD) theory for the underlying electronic structure theory. We find that the lifetime of the S2 state is more than a picosecond (with both TDDFT and EOM-CCSD). The predicted ultrafast electron diffraction spectrum exhibits numerous structural features, but weak time dependence over the course of the simulations.

    View details for DOI 10.1063/5.0203800

    View details for PubMedID 38912674

  • InteraChem: Exploring Excited States in Virtual Reality with Ab Initio Interactive Molecular Dynamics. Journal of chemical theory and computation Wang, Y., Seritan, S., Lahana, D., Ford, J. E., Valentini, A., Hohenstein, E. G., Martinez, T. J. 2022

    Abstract

    InteraChem is an ab initio interactive molecular dynamics (AI-IMD) visualizer that leverages recent advances in virtual reality hardware and software, as well as the graphical processing unit (GPU)-accelerated TeraChem electronic structure package, in order to render quantum chemistry in real time. We introduce the exploration of electronically excited states via AI-IMD using the floating occupation molecular orbital-complete active space configuration interaction method. The optimization tools in InteraChem enable identification of excited state minima as well as minimum energy conical intersections for further characterization of excited state chemistry in small- to medium-sized systems. We demonstrate that finite-temperature Hartree-Fock theory is an efficient method to perform ground state AI-IMD. InteraChem allows users to track electronic properties such as molecular orbitals and bond order in real time, resulting in an interactive visualization tool that aids in the interpretation of excited state chemistry data and makes quantum chemistry more accessible for both research and educational purposes.

    View details for DOI 10.1021/acs.jctc.2c00005

    View details for PubMedID 35649124

  • The non-adiabatic nanoreactor: towards the automated discovery of photochemistry CHEMICAL SCIENCE Pieri, E., Lahana, D., Chang, A. M., Aldaz, C. R., Thompson, K. C., Martinez, T. J. 2021

    View details for DOI 10.1039/d1sc00775k

    View details for Web of Science ID 000648669700001

  • The non-adiabatic nanoreactor: towards the automated discovery of photochemistry. Chemical science Pieri, E., Lahana, D., Chang, A. M., Aldaz, C. R., Thompson, K. C., Martínez, T. J. 2021; 12 (21): 7294-7307

    Abstract

    The ab initio nanoreactor has previously been introduced to automate reaction discovery for ground state chemistry. In this work, we present the nonadiabatic nanoreactor, an analogous framework for excited state reaction discovery. We automate the study of nonadiabatic decay mechanisms of molecules by probing the intersection seam between adiabatic electronic states with hyper-real metadynamics, sampling the branching plane for relevant conical intersections, and performing seam-constrained path searches. We illustrate the effectiveness of the nonadiabatic nanoreactor by applying it to benzene, a molecule with rich photochemistry and a wide array of photochemical products. Our study confirms the existence of several types of S0/S1 and S1/S2 conical intersections which mediate access to a variety of ground state stationary points. We elucidate the connections between conical intersection energy/topography and the resulting photoproduct distribution, which changes smoothly along seam space segments. The exploration is performed with minimal user input, and the protocol requires no previous knowledge of the photochemical behavior of a target molecule. We demonstrate that the nonadiabatic nanoreactor is a valuable tool for the automated exploration of photochemical reactions and their mechanisms.

    View details for DOI 10.1039/d1sc00775k

    View details for PubMedID 34163820

    View details for PubMedCentralID PMC8171323

  • Performance of Coupled-Cluster Singles and Doubles on Modern Stream Processing Architectures. Journal of chemical theory and computation Fales, B. S., Curtis, E. R., Johnson, K. G., Lahana, D., Seritan, S., Wang, Y., Weir, H., Martinez, T. J., Hohenstein, E. G. 2020

    Abstract

    We develop a new implementation of coupled-cluster singles and doubles (CCSD) optimized for the most recent graphical processing unit (GPU) hardware. We find that a single node with 8 NVIDIA V100 GPUs is capable of performing CCSD computations on roughly 100 atoms and 1300 basis functions in less than 1 day. Comparisons against massively parallel implementations of CCSD suggest that more than 64 CPU-based nodes (each with 16 cores) are required to match this performance.

    View details for DOI 10.1021/acs.jctc.0c00336

    View details for PubMedID 32567305