JCP Spotlight Collections–

Perspective: Relativistic Effects
Jochen Autschbach
Department of Chemistry, State University of New York at Buffalo, New York 14260-3000, USA

Abstract  This perspective article discusses some broadly-known and some less broadly-known consequences of Einstein's special relativity in quantum chemistry, and provides a brief outline of the theoretical methods currently in use, along with a discussion of recent developments and selected applications. The treatment of the electron correlation problem in relativistic quantum chemistry methods, and expanding the reach of the available relativistic methods to calculate all kinds of energy derivative properties, in particular spectroscopic and magnetic properties, requires on-going efforts.

J. Chem. Phys. 136, 150902 (2012)

See Collection

Perspective on Density Functional Theory
Kieron Burke
University of California, Irvine

Abstract  Density functional theory (DFT) is an incredible success story. The low computational cost, combined with useful (but not yet chemical) accuracy, has made DFT a standard technique in most branches of chemistry and materials science. Electronic structure problems in a dazzling variety of fields are currently being tackled. However, DFT has many limitations in its present form: Too many approximations, failures for strongly correlated systems, too slow for liquids, etc. This perspective reviews some recent progress and ongoing challenges.

J. Chem. Phys. 136, 150901 (2012)

See Collection

Hydrogen: A Fresh Look at High Pressure
Roald Hoffmann, Vanessa Labet, Paulina Gonzalez-Morelos, Neil Ashcroft
Cornell University

Abstract  Nobel Laureate and Professor Emeritus of Chemistry at Cornell University Roald Hoffmann joins colleagues Vanessa Labet and Neil Ashcroft in talking about their work on hydrogen at very high pressures. While at atmospheric pressures the hydrogen molecule remains one of the few exactly solvable problems as a diatomic molecule, it is not a solved problem under extreme pressure where the molecule’s properties change and the system becomes, as Hoffmann says, “the subject of intense experimental research and an important problem” .

J. Chem. Phys. 136, 074501 (2012)
J. Chem. Phys. 136, 074502 (2012)
J. Chem. Phys. 136, 074503 (2012)
J. Chem. Phys. 136, 074504 (2012)

See Collection

Abstract  Graphene is a single sheet of carbon atoms that constitutes the basic building block of macroscopic graphite crystals. Held together by a backbone of sp² hybrids, graphene's 2p orbitals form π state bands that delocalize over an entire 2-dimensional macroscopic carbon sheet leading to a number of unusual characteristics that include large electrical and thermal conductivities. Recent discoveries have provided simple methods (e.g. mechanical cleavage of graphite) for preparing laboratory scale samples that can be used to investigate the fundamental physical and chemical characteristics of graphene. In addition a number of techniques have emerged that show promise for producing large-scale samples with the ultimate goal of developing devices that take advantage of graphene's unusual properties. As large samples become available, the possibility grows for applications of this material in solar cell technology (as flexible, transparent electrodes), in composite material development, and in electronic devices.

J. Chem. Phys. 135, 050901 (2011)

See Collection

Water Cluster Mediated Atmospheric Chemistry
Veronica Vaida
University of Colorado

Listen now to the interview Right-click to download MP3 file.

Abstract  The importance of water in atmospheric and environmental chemistry initiated recent studies with results documenting catalysis, suppression and anti-catalysis of thermal and photochemical reactions due to hydrogen bonding of reagents with water. Water, even one water molecule in binary complexes, has been shown by quantum chemistry to stabilize the transition state and lower its energy. However, new results underscore the need to evaluate the relative competing rates between reaction and dissipation to elucidate the role of water in chemistry. Water clusters have been used successfully as models for reactions in gas-phase, in aqueous condensed phases and at aqueous surfaces. Fundamental issues in experimental and theoretical chemical physics remain but that work in this field accelerated recently, driven by the importance of this chemistry in planetary atmospheres including but not limited to Earth. J. Chem. Phys. 135, 020901 (2011)

See Collection

Ionic Liquids
Edward W. Castner, Jr.¹ and James F. Wishart^2
1Rutgers, The State University of New Jersey
²Brookhaven National Laboratory

Abstract  Ionic liquids are an emerging class of materials with a diverse and extraordinary set of properties. Understanding the origins of these properties and how they can be controlled by design to serve valuable practical applications presents a wide array of challenges and opportunities to the chemical physics and physical chemistry community. We highlight here some of the signi_cant progress already made and future research directions in this exciting area.

J. Chem. Phys. 132, 120901 (2010)

See Collection

Frontiers in Electronic Structure Theory
C. David Sherrill
Georgia Institute of Technology

Abstract  Current and emerging research areas in electronic structure theory promise to greatly extend the scope and quality of quantum chemical computations. Two particularly challenging problems are the accurate description of electronic near-degeneracies (as occur in bond-breaking reactions, firstrow transition elements, etc.) and the description of long-range dispersion interactions in density functional theory. Additionally, even with the emergence of reduced-scaling electronic structure methods and basis set extrapolation techniques, quantum chemical computations remain very time consuming for large molecules or large basis sets. A variety of techniques, including density fitting and explicit correlation methods, are making rapid progress toward solving these challenges.

J. Chem. Phys. 132, 110902 (2010)

See Collection

Cold and Ultracold Molecules: Spotlight on Orbiting Resonances
David W. Chandler
Sandia National Laboratories

Abstract  There is great interest in the production of cold molecules, at temperatures below 1 K, and ultracold molecules, at temperatures below 1 mK. Such molecules have potential applications in areas ranging from precision measurement to quantum information storage and processing, and quantum gases of ultracold polar molecules are expected to exhibit novel quantum phases. In addition, cold molecules open up a new domain for collision physics, dominated by long-range forces and scattering resonances. There have been major recent advances both in cooling molecules from room temperature and in forming molecules in ultracold atomic gases. As these techniques mature and cold and ultracold samples are more accessible collision studies at previously unavailable energies will be possible. This spotlight article will highlight some of the background and motivation for studying collisions at low energies and will direct readers to recent articles on the recent experimental advancements.

J. Chem. Phys. 132, 110901 (2010)

See Collection