Anna I. Krylov - US grants

Anna Krylov of the University of Southern California is supported by a CAREER grant from the Theoretical and Computational Chemistry Program to develop electronic structure methods for excited states to treat spin-orbit coupling, non-adiabatic coupling, and spin-forbidden relaxation. Applications include halomethyl radicals and singlet diradicals. As part of her educational plan, Krylov will employ in her courses multimedia demonstrations, problem-solving software, and mini-research problems using a new computer lab specifically designed for the integration of teaching and research.

Accurate theoretical modeling of electronically excited molecules is a current challenge, and is needed for a detailed understanding of chemical processes such as those found in the environment and in materials synthesis. This research program is directly related to a teaching program at the undergraduate and graduate levels, which includes innovative uses of computer-based learning systems.

Anna Krylov and Wee Ling Wong of the University of Southern California, Joel Bowman of Emory University, and William Polik of Hope College are supported by the NSF Division of Chemistry, under the Cyberinfrastructure and Research Facilities Program. This collaborative project establishes a center for computational studies of electronic structure and spectroscopy of open-shell and electronically excited species, which will (i) develop a model for efficient cyber-technology transfer from the developers of state-of-the-art theoretical methods and software to prospective users whose research will be enhanced by using novel computational tools; and (ii) serve as a testbed for larger scale computational centers by demonstrating how specific needs of a focused groups of users can be addressed. To achieve these goals, training and state-of-the-art computational resources will be provided to diverse experimental groups whose research involves open-shell and electronically excited species, and tools will be developed to facilitate the interpretation of electronic structure calculations in terms of experimentally relevant observables and bonding paradigms. Feedback from experimental groups will guide the center's developments.

This project will serve a diverse community of researchers and educators whose
advanced computational needs are not currently addressed by existing models of cyber infrastructure, such as general purpose lab workstations or large shared computer facilities. With a focus on greater understanding of open-shell and electronically excited species, new theoretical methodologies will be developed and incorporated, as well as new ways of interpretating calculational results in terms of experimental observables. Training will consist of introductory and advanced web courses delivered using novel distance-learning tools, tutorials, manuals, and case studies, as well as series of focused on-site and virtual workshops. A streaming digital library of quantum chemistry concepts will be created and disseminated through the Web. The library can be used by teachers in preparation of courses at levels ranging from high school to graduate studies.

Anna Krylov of the University of Southern California is supported by the Theoretical and Computational Chemistry Program to develop electronic structure methodology for open-shell and electronically excited species, in particular for those with strongly interacting electronic states of different nature. The proposed program capitalizes on the PI's recent advances in developing new equation-of-motion (EOM) coupled-cluster (CC) methods, which extend this robust and efficient technique to treat diradicals, triradicals, and bond-breaking. The following methodological developments are planned: (i) exploring higher sectors of the Fock space (e.g., double spin-flip, spin-flip - (double) ionization, etc.) to extend EOM to situations with more extensive degeneracies encountered upon multiple bond-breaking, in transition metals and polyradicals; (ii) including higher excitations to achieve chemical accuracy; (iii) spin-adaptation of open-shell CC and EOM wave functions to improve accuracy in problematic cases such as spin-contaminated or unstable references. The new methodology will be applied to study electronic structure of open-shell species involved in combustion and atmospheric chemistry as well as practically relevant radical anionic reactions (i.e., benzyne and fulvene anions), in continuing collaborations with experimental groups.

This research is expected to lead to new insights into problems of environmental and technological importance, for example chemical reaction systems that are relevant to atmospheric and synthetic chemistry. This research also includes a strong component of computer code design and implementation, and will help prepare students for careers in high-tech industries where the ability to solve complex problems using sophisticated computational tools is highly valued. New computer software will be integrated into widely available electronic structure programs, making these results available to the broad chemistry community.

This Chemistry Division award supports a Research Experiences for Undergraduates (REU) site at the University of Southern California for the summers of 2007-2009. Anna Krylov is the site's Program Director. Nineteen faculty will serve as mentors and provide research projects centered on the theme of visualizing chemical processes at the molecular level. Projects include optical imaging of reaction products, femtochemistry experiments, X-ray crystallography, spectroscopy, and theoretical simulations. Ten students will be supported each summer in a ten-week program. Minority students will be recruited through contacts with institutions in the Los Angeles area with significant populations of underrepresented groups and by coordinating recruitment with the USC McNair Scholars Program. In addition, several international students supported by USC will participate in the program. Students will participate in informal evening tutorials and seminars. Visits are planned to several large research and development labs in the Los Angeles area. Students will prepare a final written paper and a poster presentation on their research. Evaluation forms will be completed by students and their future career choices monitored.

Anna Krylov of the University of Southern California is supported by an award from the Theory, Models and Computational Methods program to develop predictive ab initio methods to characterize the electronic structure of ionized and electron-attached states in model systems, such as small clusters of nucleobases, DNA hairpins or similar systems. The proposed developments are based on the equation-of-motion coupled-cluster approach for ionization potentials (EOM-IP) and electron-attached (EOM-EA) systems, which is capable of describing multiple closely lying electronic states in an accurate, robust and efficient computational scheme The PI and her research group are (i) implementing properties and analytic gradient calculations for EOM-IP-CCSD using a Frozen Natural Orbitals (FNO) approach); (ii) implementing non-iterative triples corrections for the IP-CCSD and IP-CISD methods to improve accuracy of these methods; (iii) extending the FNO scheme to EOM-EA-CCSD energies and gradient calculations; (iv) implementing efficient calculations of Dyson orbitals and other inter-state properties to aid interpretation of the results and facilitate more direct comparisons with the experiments; and (v) parallelizing and redesigning the tensor library to take advantage of modern computer architecture.

The Krylov group develops methods with the aim to study charge transport through molecular wires, which plays a central role in many important processes such as the radiative or oxidative damage in DNA, light harvesting, molecular electronics and solar energy applications. Software developed by this research group is made available to the community by being implemented in widely used software packages: Q-CHEM and SPARTAN.

This award is supported partially by a co-funding arrangement with the Office of Cyberinfrastructure (OCI).

Computational chemistry is one of the pillars of computational science, and thus its impact reaches well beyond chemistry into biomolecular and polymer physics, materials science, and condensed-matter physics. Over its long history, which stretches back more than half a century to the dawn of computation, computational chemistry has achieved a much-deserved status as a full partner with experiment in scientific discovery, yielding simulations of such high accuracy that its predictions of a variety of molecular properties may be considered "computational experiments," often with greater reliability than laboratory measurements for many chemical properties.

The history of computational chemistry endows the field not only with great experience, but also with a legacy of diverse and complex code stacks. Many molecular dynamics and quantum chemistry programs involve hundreds of thousands to even a million lines of hand-written code in a variety of languages, including Fortran-77, Fortran-90, C, and C++. While this complexity has arisen naturally from the intricacy of the problems these programs were designed to solve, it also presents a crucial obstacle to the long-term sustainability and extension of the software on ever-changing high-performance computing hardware.

The goal of the S2I2C2M2 will be to overcome these obstacles of both algorithms and culture and change the fundamental nature of computational chemistry software development. In the year-long Conceptualization Phase, S2I2C2M2 will bring together an interdisciplinary team of computational chemists, computer scientists, applied mathematicians, and computer engineers to attack the fundamental problems of software complexity and education. Three working groups will focus on the key areas of portable parallel infrastructure, general-purpose tensor algebra algorithms, and protocols for information exchange and code interoperability. In addition, experts from the S2I2C2M2 team will participate in an inaugural summer school on software development for computational chemistry.

Anna Krylov of the University of Southern California is supported by an award from the Chemical Theory, Models and Computational Chemistry program in the Chemistry Division to develop theoretical methods and robust computational tools for modeling non-linear optical (NLO) properties. The CISE/ACI CIF21 Venture Fund for Software Reuse and the Computational and Data-Enabled Science and Engineering (CDS&E) have also contributed to funding this award. Krylov and her research group are developing formalisms and implementing computational methods to compute electronic factors for two-photon absorption (2PA) within the coupled-cluster (CC) and equation-of-motion (EOM) family of methods. These developments extend the robust and accurate EOM-CC methodology to describe EOM properties. To enable applications to realistic systems (20-30 atoms, ~1000 basis functions), they capitalize on recent methodological, computational and software developments. To include the effect of the environment (e.g., protein, solvent, molecular solid) on NLO properties, they employ the Effective Fragment Potential. Krylov and coworkers are applying these new computational tools to interrogate factors determining 2PA brightness of chromophores of fluorescent proteins used for in vivo imaging.

This research promotes fundamental understanding of non-linear processes that are exploited in novel spectroscopic approaches and technology. The computer codes developed in the framework of this research, which will be widely available to the research community, can used to design better fluorescent labels for using in bioimaging to study cellular processes in live systems, photodynamic therapy, and biosensors. These tools can also be used for developing NLO materials for micro-fabrication, 3D optical data storage and nanolithography, ultra-fast electro-optic modulation and switching, and a variety of other novel nano-bio-photonics applications.

Anna Krylov of the University of Southern California is supported by an award from the Chemical Theory, Models and Computational Methods program to develop robust and accurate theoretical methods and computational tools for modeling properties of molecules when they interact with light. This award is cofunded by the Computational and Data-Enabled Science and Engineering program in the Division of Advanced Cyberinfrastructure. Krylov and her research group are interested in properties known as non-linear optical (NLO) properties. NLO properties are exploited in novel technologies such as microfabrication, 3D optical data storage and nanolithography, ultra-fast electro-optic modulation and switching, bioimaging, photodynamic therapies, and a variety of other nano-bio-photonics applications. The new tools for interpretation of experimental spectra and for the in silico design of new materials with properties matching particular application are expected to impact both fundamental and applied research (such as bioimaging and molecular electronics) on NLO properties. Computer software generated from this research are made available to the broader research community through the widely-used Q-Chem and Spartan package. Once mature, the software is distributed as open-source code.

The emphasis of this research is on open-shell species and molecules in complex environments. The proposed developments capitalize on the work conducted in the previous funding period, which included developing formalisms and implementing calculations of electronic factors for two-photon absorption (2PA) and static and dynamic polarizabilities within the coupled-cluster (CC) and equation-of-motion (EOM) family of methods. The main thrust the current work is to develop the formalisms and codes: (i) to include the effect of the environment (solvent, molecular solids, proteins) via the Effective Fragment Potential method; and (ii) for higher-order NLO properties within the EOM-CC framework, such as three-photon absorption moments and hyperpolarizabilities. The planned applications of the new methods include investigations of fundamental aspects of non-linear spectroscopy, such as: (i) the extent of (non)-locality of NLO properties and the convergence of these properties computed within polarizable embedding schemes with respect to the size of the QM region; (ii) the relative importance of the electrostatic perturbation and polarization response of the solvent versus the contribution from delocalized excited states (such as charge transfer to solvent states); and (iii) the effect of electron correlation on NLO properties, with an emphasis on open-shell systems.will be distributed as open source, similarly to our tensor library and other Q-CHEM modules. Professor Krylov is an active contributor to the Women in Science and Engineering program at USC and beyond. She continues to maintain and develop the ??Women in Theoretical and Computational Chemistry, Material Science, and Biochemistry?? webpage, promoting research by women in these areas.