"Chemists familiar with conventional quantum mechanics will applaud and benefit greatly from this particularly instructive, thorough and clearly written exposition of density functional theory: its basis, concepts, terms, implementation, and performance in diverse applications. Users of DFT for structure, energy, and molecular property computations, as well as reaction mechanism studies, are guided to the optimum choices of the most effective methods. Well done!" Paul von RaguE Schleyer "A conspicuous hole in the computational chemist's library is nicely filled by this book, which provides a wide-ranging and pragmatic view of the subject.[...It] should justifiably become the favorite text on the subject for practioneers who aim to use DFT to solve chemical problems." J. F. Stanton, J. Am. Chem. Soc. "The authors' aim is to guide the chemist through basic theoretical and related technical aspects of DFT at an easy-to-understand theoretical level. They succeed admirably." P. C. H. Mitchell, Appl. Organomet. Chem. "The authors have done an excellent service to the chemical community. [...] A Chemist's Guide to Density Functional Theory is exactly what the title suggests. It should be an invaluable source of insight and knowledge for many chemists using DFT approaches to solve chemical problems." M. Kaupp, Angew. Chem.

A Chemist's Guide to Density Functional Theory

We present a systematic study for numerical atomic basis orbitals ranging from H to Kr, which could be used in large scale $\mathrm{O}(N)$ electronic structure calculations based on density-functional theories (DFT). The comprehensive investigation of convergence properties with respect to our primitive basis orbitals provides a practical guideline in an optimum choice of basis sets for each element, which well balances the computational efficiency and accuracy. Moreover, starting from the primitive basis orbitals, a simple and practical method for variationally optimizing basis orbitals is presented based on the force theorem, which enables us to maximize both the computational efficiency and accuracy. The optimized orbitals well reproduce convergent results calculated by a larger number of primitive orbitals. As illustrations of the orbital optimization, we demonstrate two examples: the geometry optimization coupled with the orbital optimization of a ${\mathrm{C}}_{60}$ molecule and the preorbital optimization for a specific group such as proteins. They clearly show that the optimized orbitals significantly reduce the computational efforts, while keeping a high degree of accuracy, thus indicating that the optimized orbitals are quite suitable for large scale DFT calculations.

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Numerical atomic basis orbitals from H to Kr

We demonstrate a technique that uses high-order harmonic generation in molecules to probe nuclear dynamics and structural rearrangement on a subfemtosecond time scale. The chirped nature of the electron wavepacket produced by laser ionization in a strong field gives rise to a similar chirp in the photons emitted upon electron-ion recombination. Use of this chirp in the emitted light allows information about nuclear dynamics to be gained with 100-attosecond temporal resolution, from excitation by an 8-femtosecond pulse, in a single laser shot. Measurements on molecular hydrogen and deuterium agreed well with calculations of ultrafast nuclear dynamics in the H2+ molecule, confirming the validity of the method. We then measured harmonic spectra from CH4 and CD4 to demonstrate a few-femtosecond time scale for the onset of proton rearrangement in methane upon ionization.

https://science.sciencemag.org/content/sci/312/5772/424.full.pdf

Probing Proton Dynamics in Molecules on an Attosecond Time Scale

The field of cluster research can trace its origins back to the mid-nineteenth century when early studies of colloids, aerosols, and nucleation phenomena were reported. The field underwent a resurgence of interest several decades ago when well-defined clusters were observed in supersonic expansions that could be investigated using mass spectrometers. The advent of the laser provided a new dimension, enabling detailed spectroscopic observations through the probing of systems of varying size and degree of solvation. Modern interest derives from recognition that interrogating clusters provides a way of studying the energetics and dynamics of intermediate states of matter as cluster systems evolve from the gas toward the condensed state. Herein, we endeavor to highlight some of the significant advances which have been made during the past several decades that have led to a nearly explosive growth of interest in the field of cluster science. Finally, we conclude that the field will continue to expand through i...

Clusters: Structure, Energetics, and Dynamics of Intermediate States of Matter

Encapsulating atoms or molecules inside fullerene cages could give rise to a myriad of novel molecules and materials. The existence of such species is now strongly supported by a growing body of experimental evidence. Fullerene& ndash;metal complexes generally thought to be endohedral are being produced and purified in milligram quantities, and their structure and properties are beginning to be explored

Atoms in carbon cages: the structure and properties of endohedral fullerenes

Experimental evidence for a C2v (2B1) ground-state structure of the methane cation radical: ESR and ab initio CI investigations of methane cation radicals (CH4+ and CD2H2+) in neon matrixes at 4 K

ESR investigations of molecular cation radicals in neon matrices at 4 K: generation, trapping, and ion-neutral reactions

ESR spectra of MgH, CaH, SrH, and BaH molecules in their ground 2Σ+ states were measured while isolated in solid argon matrices at 4°K. The molecules were prepared by quenching metal and hydrogen atom beams in a stream of argon. g tensors and hyperfine structure (hfs) constants for interaction with H, and in the case of MgH, with 25Mg and D, were determined. For 25MgH, | Ψ (0) |2 at Mg and H nuclei were found to be 0.800(8) and 0.0663(2) a.u., respectively, in good agreement with 0.7635 and 0.03789 a.u. recently calculated by Chan and Davidson using a 953 CI wavefunction. It is evident that such elaborate calculations are necessary to obtain accurate theoretical spin densities. Hydrogen hf interaction within the group of molecules indicate less ionicity than in the corresponding diatomic fluorides although the spin density is still predominantly on the metal atoms. Metal p and d contributions are approximately derived from the observed Δg⊥ values and discussed in relation to the united‐atom model.

Hyperfine Interaction and Chemical Bonding in MgH, CaH, SrH, and BaH Molecules

Sc3 and Y3 molecules have been isolated in rare gas matrices at temperatures near 4 K. ESR spectra establish that the structure of Sc3 is an equilateral triangle at 4–30 K with a 2A′1 ground state. The possibility remains that Sc3 is a fluxional bent molecule with a very low barrier to pseudorotation. The 45Sc hyperfine splitting indicates that the unpaired electron has little s character and is delocalized in 3d orbitals on the three equivalent atoms. Y3, however, is not equilateral and is most probably a bent molecule at these temperatures with the spin again distributed over the 3d atomic orbitals, but in a 2B2 ground state. La3 was not observed and is therefore judged to be a linear orbitally degenerate molecule. Under special conditions, a cluster of exceptional stability Scx, where x≥9 is formed in neon matrices. From its uniqueness and from the hyperfine structure in its ESR spectrum, it is suggested that it may be Sc13 with an icosahedral structure. This places 12 equivalent atoms at the vertices ...

Properties of Sc3, Y3, and Sc13 molecules at low temperatures, as determined by ESR

The 14N+4 and 15N+4 molecular cation radicals have been generated by the ion–neutral reaction N+2 +N2 and isolated in solid neon matrices at 4 K for detailed ESR (electron spin resonance) investigation. Both photonionization at 16.8 eV and electron bombardment (50 eV) were used in conjunction with the neon matrix trapping technique to produce the N+4 dimer cation. The ESR results clearly show that N+4 is linear and has a 2Σμ ground electronic state. The magnetic parameters in neon are: g∥=2.0016(4) and g⊥=1.9998(2); A∥(14N)=311(1) MHz and A⊥(14N)=264(1) MHz for the central atoms and ‖A∥‖=10.4(5) MHz and ‖A⊥‖=20.4(1) MHz for the outer or terminal 14N atoms. Electronic structure information for N+4 was obtained from the ESR results and compared with ab initio CI calculations. The unpaired electron resides primarily on the inner nitrogen atoms with significant 2pσ and 2s character. Orbital characters obtained from the commonly applied free atom comparison method (FACM) were compared with the results of a Mul...

Lon B. Knight

Papers

Experimental evidence for a C2v (2B1) ground-state structure of the methane cation radical: ESR and ab initio CI investigations of methane cation radicals (CH4+ and CD2H2+) in neon matrixes at 4 K

ESR investigations of molecular cation radicals in neon matrices at 4 K: generation, trapping, and ion-neutral reactions

Hyperfine Interaction and Chemical Bonding in MgH, CaH, SrH, and BaH Molecules

Properties of Sc3, Y3, and Sc13 molecules at low temperatures, as determined by ESR

ESR and ab initio theoretical studies of the cation radicals 14N+4 and 15N+4: The trapping of ion–neutral reaction products in neon matrices at 4 K