What is Crystal structures?4 answersCrystal structures refer to the arrangement of atoms or molecules in a crystalline material ^[Prentice]. Crystalline materials have both short-range and long-range order, unlike amorphous materials which only have short-range order ^[Prentice]. The structure of a crystal depends on factors such as the type of bond, the number and diversity of atoms, and the repetition associated with the network ^[Wilkening]. The most energetically stable crystal structures are those that arrange their atoms or molecules in the most compact way possible ^[Wilkening]. Different types of crystals, such as covalent, metallic, and ionic crystals, can be categorized based on the nature of their chemical bonding forces ^[Wilkening]. The structure of a crystal can be characterized by its coordination polyhedron, coordination number, and the ratio of radii of the coordinated ions ^[Wilkening]. The Pauling rules provide conditions for maximum compactness and ionic character in crystalline structures ^[Wilkening].
What is chiral symmetry?4 answersChiral symmetry is a fundamental concept in quantum physics that is relevant to both condensed matter and particle physics. It refers to a symmetry between left-handed and right-handed particles, where the behavior of a system remains unchanged when left-handed particles are transformed into right-handed particles and vice versa. The overlap-Dirac operator is a method used to realize chiral fermions without explicitly calculating the low modes of the Wilson-Dirac operator. It involves introducing a projection operator and formulating the exact sign function and overlap-Dirac operator with a contour-integral form. This method is parallelizable and suitable for multi-core/multi-GPGPU systems. The quality of chiral symmetry achieved with this method is sufficient for double precision calculations.
What is chiral superconductor?4 answersChiral superconductors are a unique class of unconventional superconductors where the superconducting order parameter winds clockwise or counter-clockwise in momentum space. They represent a topologically non-trivial system with implications for topological quantum computing. Intrinsic chiral superconductors are rare, with examples including heavy fermion metals (UTe$_2$, UPt$_3$) and perovskite superconductor Sr$_2$RuO$_4$. Chiral molecules with neither mirror nor inversion symmetry have been investigated, and a combination of superconductivity with chiral molecules may lead to a spin-polarized ground state for chiral superconductivity. Chiral superconductors break time-reversal symmetry and have circulating Cooper pairs around a unique chiral axis. NbGe${}_{2}$ is a type-I full-gap bulk chiral superconductor with Kramers-Weyl fermions and enhanced critical field. Chiral spin liquid states on the triangular lattice can exhibit topological superconductivity.
Do helically chiral structures rotate the plane of polarized light?4 answersHelically chiral structures have the ability to rotate the plane of polarized light. This rotation is induced by the mirror symmetry breaking of the unit-cell geometry, resulting in optical activity and polarization selectivity. The rotation of light polarization is caused by chirality, either in the molecules making up the substance or in the helical arrangement of atomic or molecular constituents in a crystal. Artificial chiral metamaterials can also exhibit strong rotatory power by engineering intra-molecular couplings. The strong inter-molecular coupling between adjacent chiral metamolecules can lead to a broadband enhanced rotating ability with pure rotation of linearly polarized electromagnetic waves. Therefore, helically chiral structures can indeed rotate the plane of polarized light.
What is political structure?5 answersPolitical structure refers to the organization and functioning of a political system, including the formation and organization of government bodies, the relationships between these bodies, and the relationship between these bodies and other institutionalized forms of political systems. It is the level of the social structure where normative decisions are made, including decisions on governing exchanges among different groups or specific interests, decision-making processes, and decisions related to the mode of production and distribution of social resources. The political structure provides a framework for politicians and influences their conduct and the performance of government. It is distinct from the political system, which refers to the specific set of political elements within the structure that are particular to each society. Defining and understanding the political structure and system is important for rigorous research and analysis in political science.
What is organisaitional structure?5 answersOrganizational structure refers to the way in which a company divides its labor into distinct tasks and coordinates them. It involves the allocation of formal responsibilities and the establishment of formal links between employees. Authority, which is the right to make decisions, give orders, and direct the work of others, is an important aspect of organizational structure. Delegation of authority allows for the transfer of decision-making power to lower-level employees. The structure of an organization plays a critical role in its survival, as it affects resource management, efficiency, communication, collaboration, and motivation. Process innovation and organizational design are key factors in improving performance and achieving competitive advantage. Organelle structures, which bridge the link between a company and its environment, can be used to implement manufacturing strategies and enhance performance.