Demonstrating that the non orthogonal orbital optimized coupled cluster model converges to full configuration interaction

Coupled cluster (CC) methods are among the most accurate methods in quantum chemistry. However, the standard CC linear response formulation is not gauge invariant resulting in errors when modelling properties like optical rotation and electron circular dichroism. Including an explicit unitary orbital rotation in the CC Lagrangian makes the linear response function gauge invariant, but the resulting models are not equivalent to full configuration interaction (FCI) in the untruncated limit. In this contribution, such methods are briefly discussed and it is demonstrated that methods using a nonorthogonal orbital transformation, such as nonorthogonal orbital optimized CC (NOCC), can converge to FCI in the untruncated limit. This has been disputed in the literature.Comment: 18 page

A Cultural Criminology of ‘New’ Jihad: Insights from Propaganda Magazines

The backgrounds and modus operandi of more recent jihadi terrorists tend to share factors and characteristics more typically associated with non-political violence such as mass- killings and gang violence. Their attacks, moreover, seem to have been precipitated not by the direct instructions of a formal hierarchy but by the encouragement of propaganda produced and disseminated by networked, media-savvy terrorist groups. It is necessary to explain how these ‘recruitment’ efforts work. Cultural criminology with its understanding of the relationship between mediated meaning and individual experience, can provide such an analysis. The paper presents a qualitative document analysis of 32 propaganda magazines produced by the Islamic State and Al-Qaeda. It demonstrates that they contain significantly more than religious rhetoric and military strategy. Rather, they are part of a process that crystalizes a jihadi subculture that appeals to disaffected and/or marginalized, excitement- seeking youths. The magazines cultivate violence by constructing a militarized style that celebrates outlaw status, where violence is eroticized and aestheticized. They idealize the notion of a jihadi terrorist that is tough and willing to commit brutal violence. The lifestyle portrayed offers the possibility of heroism, excitement, belonging and imminent fame, themes often espoused by conventional, Western consumer culture. The magazines occasionally draw on street jargon, urban music, fashion, films and video games. The subcultural model of jihadi propaganda we explicate provides a novel way of understanding terrorist recruiting tactics and motivations that are not necessarily in opposition to contemporary conventional criminal and ‘mainstream’ cultures, but in resonance with them

Crossing conditions in coupled cluster theory

We derive the crossing conditions at conical intersections between electronic states in coupled cluster theory, and show that if the coupled cluster Jacobian matrix is nondefective, two (three) independent conditions are correctly placed on the nuclear degrees of freedom for an inherently real (complex) Hamiltonian. Calculations using coupled cluster theory on an $2 {^{1}}A' / 3 {^{1}}A'$ conical intersection in hypofluorous acid illustrate the nonphysical artifacts associated with defects at accidental same-symmetry intersections. In particular, the observed intersection seam is folded about a space of the correct dimensionality, indicating that minor modifications to the theory are required for it to provide a correct description of conical intersections in general. We find that an accidental symmetry allowed $1 {^{1}}A" / 2 {^{1}}A"$ intersection in hydrogen sulfide is properly described, showing no artifacts as well as linearity of the energy gap to first order in the branching plane.Comment: 9 pages and 4 figure

Effects of 9-hour time zone changes on fatigue and circadian rhythms of sleep/wake and core temperature

Physiological and psychological disruptions caused by transmeridian flights may affect the ability of flight crews to meet operational demands. To study these effects, 9 Royal Norwegian Airforces P3-Orion crewmembers flew from Norway to California (-9 hr), and back (+9 hr). Rectal temperature, heart rate and wrist activity were recorded every 2 min, fatigue and mood were rated every 2 hr during the waking day, and logs were kept of sleep times and ratings. Subjects also completed 4 personality inventories. The time-zone shifts produced negative changes in mood which persisted longer after westward flights. Sleep quality (subjective and objective) and duration were slightly disrupted (more after eastward flights). The circadian rhythms of sleep/wake and temperature both completed the 9-hr delay by day 5 in California, although temperature adjusted more slowly. The size of the delay shift was significantly correlated with scores on extraversion and achievement need personality scales. Response to the 9-hr advance were more variable. One subject exhibited a 15-hr delay in his temperature rhythm, and an atypical sleep/nap pattern. On average, the sleep/wake cycle (but not the temperature rhythm), completed the 9-hr advance by the end of the study. Both rhythms adapted more slowly after the eastward flight

Modulation of Mid‐Holocene African Rainfall by Dust Aerosol Direct and Indirect Effects

Climate model simulations of the mid‐Holocene (MH) consistently underestimate northern African rainfall for reasons not fully understood. While most models incorporate orbital forcing and vegetation feedbacks, they neglect dust reductions associated with greater vegetation cover. Here we simulate the MH climate response to reduced Saharan dust using CESM CAM5‐chem, which resolves direct and indirect dust aerosol effects. Direct aerosol effects increase Saharan and Sahel convective rainfall by ~16% and 8%. In contrast, indirect aerosol effects decrease stratiform rainfall, damping the dust‐induced total rainfall increase by ~13% in the Sahara and ~59% in the Sahel. Sensitivity experiments indicate the dust‐induced precipitation anomaly in the Sahara and Sahel (0.27 and 0.18 mm/day) is smaller than the anomaly from MH vegetation cover (1.19 and 1.08 mm/day). Although sensitive to dust radiative properties, sea surface temperatures, and indirect aerosol effect parameterization, our results suggest that dust reductions had competing effects on MH African rainfall.Plain Language SummarySix thousand years ago, changes in Earth’s orbit led to greater summer season solar radiation over northern Africa. The increase in energy resulted in higher rainfall amounts, widespread vegetation, and reduced dust aerosols over regions that today are desert. In this study we use a climate model, CESM CAM5‐chem, that accounts for the ways dust aerosols interact with sunlight and cloud droplets to examine how the reduction in Saharan dust during this past humid time affected rainfall. When dust aerosols are reduced in the model, more sunlight reaches the surface, the Sahara warms, and convective rainfall from the West African Monsoon increases. However, through dust‐cloud droplet interactions, the same reduction in dust decreases nonconvective rainfall, which is less prevalent during the monsoon season but still important, and thus dampens the total rainfall increase. Overall, dust reduction leads to a rainfall response that is dependent on rainfall type. Lastly, we compare the rainfall response of reducing dust to that of increasing vegetation cover and find that while important, the response from dust is considerably weaker.Key PointsChanges in direct dust aerosol effects from reduced mid‐Holocene Saharan dust loading increase convective rainfall in northern AfricaChanges in indirect dust aerosol effects weaken total precipitation increases by limiting stratiform rainfall, particularly in the SahelThe African rainfall response to total dust aerosol effects is lower than a previous study and substantially less than vegetation forcingPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149324/1/grl58759-sup-0001-2018GL081225-SI.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149324/2/grl58759_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149324/3/grl58759.pd

Emerging Asian aerosol patterns

Anthropogenic aerosol emissions over Asia are changing rapidly, both in composition and spatial distribution1. The Shared Socioeconomic Pathways (SSPs), potential narratives of development used by the Intergovernmental Panel for Climate Change in future projections, span a range of influences of aerosols on climate over the next decades. Several of these narratives project the continuation of a trend manifested in observations since 2010, with a clear dipole between South and East Asia. The patterns of radiative forcing that result from these distributions of aerosols will differ from those of the late 20th century. They may instigate large-scale atmospheric responses that could have wide ranging impacts on climate and society well beyond the aerosol source regions. South and East Asia are particularly vulnerable to climate change because of strong seasonal variations in precipitation, high average temperature, and very high population density. Therefore, any aerosol impacts on the strength or seasonal variations in monsoon rainfall, freshwater availability, or climate extremes, will incur large societal costs. We urge the scientific community to make definite progress towards understanding and quantifying the impacts of Asian aerosols and to tackle the potentially large regional and hemispheric implications of these emerging trends

Observation of ultrafast intersystem crossing in thymine by extreme ultraviolet time-resolved photoelectron spectroscopy

We studied the photoinduced ultrafast relaxation dynamics of the nucleobase thymine using gas-phase time-resolved photoelectron spectroscopy. By employing extreme ultraviolet pulses from high harmonic generation for photoionization, we substantially extend our spectral observation window with respect to previous studies. This enables us to follow relaxation of the excited state population all the way to low-lying electronic states including the ground state. In thymine, we observe relaxation from the optically bright1IIII* state of thymine to a dark1nII* state within 80 ± 30 fs. The1nII* state relaxes further within 3.5 ± 0.3 ps to a low-lying electronic state. By comparison with quantum chemical simulations, we can unambiguously assign its spectroscopic signature to the3IIII* state. Hence, our study draws a comprehensive picture of the relaxation mechanism of thymine including ultrafast intersystem crossing to the triplet manifold

Climate responses to anthropogenic emissions of short-lived climate pollutants

Policies to control air quality focus on mitigating emissions of aerosols and their precursors, and other short-lived climate pollutants (SLCPs). On a local scale, these policies will have beneficial impacts on health and crop yields, by reducing particulate matter (PM) and surface ozone concentrations; however, the climate impacts of reducing emissions of SLCPs are less straightforward to predict. In this paper we consider a set of idealised, extreme mitigation strategies, in which the total anthropogenic emissions of individual SLCP emissions species are removed. This provides an upper bound on the potential climate impacts of such air quality strategies. We focus on evaluating the climate responses to changes in anthropogenic emissions of aerosol precursor species: black carbon (BC), organic carbon (OC) and sulphur dioxide (SO2). We perform climate integrations with four fully coupled atmosphere-ocean global climate models (AOGCMs), and examine the effects on global and regional climate of removing the total land-based anthropogenic emissions of each of the three aerosol precursor species. We find that the SO2 emissions reductions lead to the strongest response, with all three models showing an increase in surface temperature focussed in the northern hemisphere high latitudes, and a corresponding increase in global mean precipitation and run-off. Changes in precipitation and run-off patterns are driven mostly by a northward shift in the ITCZ, consistent with the hemispherically asymmetric warming pattern driven by the emissions changes. The BC and OC emissions reductions give a much weaker forcing signal, and there is some disagreement between models in the sign of the climate responses to these perturbations. These differences between models are due largely to natural variability in sea-ice extent, circulation patterns and cloud changes. This large natural variability component to the signal when the ocean circulation and sea-ice are free-running means that the BC and OC mitigation measures do not necessarily lead to a discernible climate response

Methane Production Pathway Regulated Proximally by Substrate Availability and Distally by Temperature in a High-Latitude Mire Complex

Projected 21st century changes in high-latitude climate are expected to have significant impacts on permafrost thaw, which could cause substantial increases in emissions to the atmosphere of carbon dioxide (CO2) and methane (CH4, which has a global warming potential 28 times larger than CO2 over a 100-year horizon). However, predicted CH4 emission rates are very uncertain due to difficulties in modeling complex interactions among hydrological, thermal, biogeochemical, and plant processes. Methanogenic production pathways (i.e., acetoclastic [AM] and hydrogenotrophic [HM]) and the magnitude of CH4 emissions may both change as permafrost thaws, but a mechanistic analysis of controls on such shifts in CH4 dynamics is lacking. In this study, we reproduced observed shifts in CH4 emissions and production pathways with a comprehensive biogeochemical model (ecosys) at the Stordalen Mire in subarctic Sweden. Our results demonstrate that soil temperature changes differently affect AM and HM substrate availability, which regulates magnitudes of AM, HM, and thereby net CH4 emissions. We predict very large landscape-scale, vertical, and temporal variations in the modeled HM fraction, highlighting that measurement strategies for metrics that compare CH4 production pathways could benefit from model informed scale of temporal and spatial variance. Finally, our findings suggest that the warming and wetting trends projected in northern peatlands could enhance peatland AM fraction and CH4 emissions even without further permafrost degradation