Valence Virtual Orbitals: An Unambiguous ab Initio Quantification of the LUMO Concept.

UNLABELLED: Many chemical concepts hinge on the notion of an orbital called the lowest unoccupied molecular orbital, or LUMO. This hypothetical orbital and the much more concrete highest occupied molecular orbital (HOMO) constitute the two "frontier orbitals", which rationalize a great deal of chemistry. A viable LUMO candidate should have a sensible energy value, a realistic shape with amplitude on those atoms where electron attachment or reduction or excitation processes occur, and often an antibonding correspondence to one of the highest occupied MOs. Unfortunately, today's quantum chemistry calculations do not yield useful empty orbitals. Instead, the empty canonical orbitals form a large sea of orbitals, where the interesting valence antibonds are scrambled with the basis set's polarization and diffuse augmentations. The LUMO is thus lost within a continuum associated with a detached electron, as well as many Rydberg excited states. A suitable alternative to the canonical orbitals is proposed, namely, the valence virtual orbitals. VVOs are found by a simple algorithm based on singular value decomposition, which allows for the extraction of all valence-like orbitals from the large empty canonical orbital space. VVOs are found to be nearly independent of the working basis set. The utility of VVOs is demonstrated for construction of qualitative MO diagrams, for prediction of valence excited states, and as starting orbitals for more sophisticated calculations. This suggests that VVOs are a suitable realization of the LUMO, LUMO + 1, ... CONCEPT: VVO generation requires no expert knowledge, as the number of VVOs sought is found by counting s-block atoms as having only a valence s orbital, transition metals as having valence s and d, and main group atoms as being valence s and p elements. Closed shell, open shell, or multireference wave functions and elements up to xenon may be used in the present program.

Activity reconstruction of Rangifer tarandus feet in Fennoscandian -archaeology: Methodological considerations and application to archaeological material from two Sámi habitation sites.

OBJECTIVE: This study explores the presence and prevalence of working Rangifer tarandus tarandus (domestic reindeer) through entheseal changes present in Rangifer tarandus phalanges at the Sámi habitation sites of Juikenttä and Nukkumajoki, located in Finland and dating from the 14th to the 18th centuries. MATERIALS: Modern samples (n = 23 phalanges, Rangifer tarandus fennicus; n = 60 phalanges, Rangifer tarandus tarandus non-working; n = 72 phalanges, Rangifer tarandus tarandus working) with known life histories. Archaeological samples (n = 22 phalanges, Juikenttä; n = 118 phalanges, Nukkumajoki). METHODS: We analysed entheseal changes on the first and second phalanges of both the thoracic and pelvic limbs. The minute movements of reindeer feet create entheseal changes which are specific to different activity patterns. This analysis was compared to the results obtained from long-bone analysis. RESULTS: Our results show the presence of working reindeer at both sites and are consistent with previous analysis of the long bones found at the site. CONCLUSIONS: This archaeological application of phalangeal entheseal changes suggests that reindeer phalanges may be used to assess both the presence and proportion of working animals in an assemblage. SIGNIFICANCE: This study provides more evidence for the use of working reindeer as early as the 14th century in Northern Finland. This work also helps to provide archaeological evidence for Sámi subsistence patterns, as well as proving new tools for zooarchaeological assessment. LIMITATIONS: Small sample size and taphonomy may affect assessment. Additionally, entheseal changes take time to envelope and may under-represent the number of working reindeer. SUGGESTIONS FOR FURTHER RESEARCH: Assessment of additional modern and archaeological samples.

Frontier Lapita interaction with resident Papuan populations set the stage for initial peopling of the Pacific.

The initial peopling of the remote Pacific islands was one of the greatest migrations in human history, beginning three millennia ago by Lapita cultural groups. The spread of Lapita out of an ancestral Asian homeland is a dominant narrative in the origins of Pacific peoples, and although Island New Guinea has long been recognized as a springboard for the peopling of Oceania, the role of Indigenous populations in this remarkable phase of exploration remains largely untested. Here, we report the earliest evidence for Lapita-introduced animals, turtle bone technology and repeated obsidian import in southern New Guinea 3,480-3,060 years ago, synchronous with the establishment of the earliest known Lapita settlements 700 km away. Our findings precede sustained Lapita migrations and pottery introductions by several centuries, occur alongside Indigenous technologies and suggest continued multicultural influences on population diversity despite language replacement. Our work shows that initial Lapita expansion throughout Island New Guinea was more expansive than previously considered, with Indigenous contact influencing migration pathways and island-hopping strategies that culminated in rapid and purposeful Pacific-wide settlement. Later Lapita dispersals through New Guinea were facilitated by earlier contact with Indigenous populations and profoundly influenced the region as a global centre of cultural and linguistic diversity.

Tendons and ligaments of the Rangifer tarandus metapodial and hoof.

Rangifer tarandus, the northern species including both reindeer and caribou, is a pillar of northern ecosystems and the lives of northern peoples. As the only domestic cervid, reindeer are important not only to the herders and hunters who presently interact with them, but also to zooarchaeologists and palaeontologists tracing their histories. Unfortunately, limited anatomical information on Rangifer tarandus muscles is available beyond descriptions of the large muscle groups. The lower limb and hoof in particular is poorly documented. This is problematic, as this important body part has the potential to be informative in zooarchaeological analyses of habitual activity, especially in regards to historical animal health, movement, and habitual activity. Better understanding of the hoof can additionally be useful to herders and veterinarians seeking to provide veterinary care for living animals. This study has used dissections and comparisons of the reindeer hoof with other domestic ungulates to document both the common and unique structures in Rangifer tarandus hooves, including the presence and attachment points of these structures. As these structures have proved unique, especially in regards to the dewclaw, it is important that other ungulates not be used exclusively in the analysis of Rangifer tarandus remains.

Emergence of a Neolithic in highland New Guinea by 5000 to 4000 years ago.

The emergence of agriculture was one of the most notable behavioral transformations in human history, driving innovations in technologies and settlement globally, referred to as the Neolithic. Wetland agriculture originated in the New Guinea highlands during the mid-Holocene (8000 to 4000 years ago), yet it is unclear if there was associated behavioral change. Here, we report the earliest figurative stone carving and formally manufactured pestles in Oceania, dating to 5050 to 4200 years ago. These discoveries, at the highland site of Waim, occur with the earliest planilateral axe-adzes in New Guinea, the first evidence for fibercraft, and interisland obsidian transfer. The combination of symbolic social systems, complex technologies, and highland agricultural intensification supports an independent emergence of a Neolithic ~1000 years before the arrival of Neolithic migrants (Lapita) from Southeast Asia.

A computational study on the characteristics of open-shell H-bonding interaction between carbamic acid (NH2COOH) and HO2, HOS or HSO radicals.

Quantum chemical computations were applied to investigate the characteristics of open-shell hydrogen-bonding interactions in the complexes of carbamic acid (NH2COOH, CA) with HO2, HOS and HSO radicals. All the resulting complexes were studied using the MP2, B3PW91 and B3LYP computational levels and 6311++G** basis set. Geometry optimizations show that the O-H⋯O contact is stronger than N-H⋯O and S-H⋯O. The interaction energies revealed that all the radicals form stronger hydrogen bonded complexes at site-1, as confirmed by electron-density (ρ) and corresponding Laplacian (∇2ρ) values obtained by atoms in molecule (AIM) analysis. Non-covalent interaction and reduced density gradient analysis support the AIM results. Natural bond orbital analysis was employed to obtain the stabilization energies (E(2)) due to charge delocalization between the interacting units. Energy decomposition analysis suggests that, for the title complexes, the exchange energy makes a larger contribution to the total interaction energy compared to other energy terms. Graphical abstract Open-shell H-bondinginteraction between carbamic acid (NH2COOH) and HO2, HOS or HSOradicals.

UV-visible spectroscopy of macrocyclic alkyl, nitrosyl and halide complexes of cobalt and rhodium. Experiment and calculation.

Transition metal complexes (NH3)5CoX(2+) (X = CH3, Cl) and L(H2O)MX(2+), where M = Rh or Co, X = CH3, NO, or Cl, and L is a macrocyclic N4 ligand are examined by both experiment and computation to better understand their electronic spectra and associated photochemistry. Specifically, irradiation into weak visible bands of nitrosyl and alkyl complexes (NH3)5CoCH3(2+) and L(H2O)M(III)X(2+) (X = CH3 or NO) leads to photohomolysis that generates the divalent metal complex and ˙CH3 or ˙NO, respectively. On the other hand, when X = halide or NO2, visible light photolysis leads to dissociation of X(-) and/or cis/trans isomerization. Computations show that visible bands for alkyl and nitrosyl complexes involve transitions from M-X bonding orbitals and/or metal d orbitals to M-X antibonding orbitals. In contrast, complexes with X = Cl or NO2 exhibit only d-d bands in the visible, so that homolytic cleavage of the M-X bond requires UV photolysis. UV-Vis spectra are not significantly dependent on the structure of the equatorial ligands, as shown by similar spectral features for (NH3)5CoCH3(2+) and L(1)(H2O)CoCH3(2+).