Singlet-triplet energy gap in methylene using many-body methods

1985 ◽  
Vol 113 (3) ◽  
pp. 271-274 ◽  
Author(s):  
Samuel J. Cole ◽  
George D. Purvis ◽  
Rodney J. Bartlett
Keyword(s):  
2011 ◽  
Vol 13 (10) ◽  
pp. 4709 ◽  
Author(s):  
Vincenzo Barone ◽  
Ivo Cacelli ◽  
Alessandro Ferretti ◽  
Susanna Monti ◽  
Giacomo Prampolini

Author(s):  
Vladimir Kresin ◽  
Sergei Ovchinnikov ◽  
Stuart Wolf

For the past almost fifty years, scientists have been trying to explain the phenomenon of superconductivity. The mechanism is the key ingredient of microscopic theory, which was developed by Bardeen, Cooper, and Schrieffer in 1957. The theory also introduced the basic concepts of pairing, coherence length, energy gap, and so on. Since then, microscopic theory has undergone an intensive development. This book provides a very detailed theoretical treatment of the key mechanisms of superconductivity, including the current state of the art (phonons, magnons, plasmons). In addition, the book contains descriptions of the properties of the key superconducting compounds that are of the most interest for science and applications. For many years, there has been a search for new materials with higher values of the main parameters, such as the critical temperature and critical current. At present, the possibility of observing superconductivity at room temperature has become perfectly realistic. That is why the book is especially concerned with high-Tc systems such as high-Tc oxides, hydrides with record values for critical temperature under high pressure, nanoclusters, and so on. A number of interesting novel superconducting systems have been discovered recently, including topological materials, interface systems, and intercalated graphene. The book contains rigorous derivations based on statistical mechanics and many-body theory. The book also provides qualitative explanations of the main concepts and results. This makes the book accessible and interesting for a broad audience.


2019 ◽  
Vol 55 (10) ◽  
pp. 1450-1453 ◽  
Author(s):  
Chengkai Zhang ◽  
Yanqian Zhao ◽  
Dandan Li ◽  
Jiejie Liu ◽  
Heguo Han ◽  
...  

Two-photon active photosensitizers showed relatively strong intersystem crossing facilitating 1O2 generation and cell apoptosis with near-infrared excitation.


2020 ◽  
Vol 9 (9) ◽  
pp. 1249-1249
Author(s):  
Shiv Kumar ◽  
Pachaiyappan Rajamalli ◽  
David B. Cordes ◽  
Alexandra M. Z. Slawin ◽  
Eli Zysman‐Colman

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1236 ◽  
Author(s):  
Hong-Jui Huang ◽  
Sonai Seenithurai ◽  
Jeng-Da Chai

At the nanoscale, it has been rather troublesome to properly explore the properties associated with electronic systems exhibiting a radical nature using traditional electronic structure methods. Graphene nanoflakes, which are graphene nanostructures of different shapes and sizes, are typical examples. Recently, TAO-DFT (i.e., thermally-assisted-occupation density functional theory) has been formulated to tackle such challenging problems. As a result, we adopt TAO-DFT to explore the electronic properties associated with diamond-shaped graphene nanoflakes with n = 2–15 benzenoid rings fused together at each side, designated as n-pyrenes (as they could be expanded from pyrene). For all the n values considered, n-pyrenes are ground-state singlets. With increasing the size of n-pyrene, the singlet-triplet energy gap, vertical ionization potential, and fundamental gap monotonically decrease, while the vertical electron affinity and symmetrized von Neumann entropy (which is a quantitative measure of radical nature) monotonically increase. When n increases, there is a smooth transition from the nonradical character of the smaller n-pyrenes to the increasing polyradical nature of the larger n-pyrenes. Furthermore, the latter is shown to be related to the increasing concentration of active orbitals on the zigzag edges of the larger n-pyrenes.


1985 ◽  
Vol 63 (12) ◽  
pp. 3582-3586 ◽  
Author(s):  
A. C. Hopkinson ◽  
M. H. Lien

Abinitio molecular orbital calculations with a 6-31G* basis set have been used to optimise structures for CX+, CHX+•, CHX (both singlets and triplets), H2CX+ and H3CX (X = H, CH3, NH2, OH, F, CN, and NC). Single point calculations were then performed on the 6-31G* optimised structures using a configuration interaction method involving all single and double excitations from the valence shell. Stabilisation energies for the carbocations are compared with those already reported for H2CX+. For the carbenes the single-triplet energy gap is examined as a function of substituent and the stabilisation energies of the singlet carbenes are compared with those of the isoelectronic carbocations H2CX+. Proton affinities are reported for the singlet carbenes and are compared with the proton affinities of similarly substituted ethylenes, H2C=CHX.


2018 ◽  
Vol 6 (6) ◽  
pp. 1700847 ◽  
Author(s):  
Zhiwei Zhang ◽  
Junji Zhang ◽  
Bin Wu ◽  
Xin Li ◽  
Yi Chen ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document