Molecular orbitals are usually constructed by combining atomic orbitals or hybrid orbitals from each atom of the molecule, or other molecular orbitals from groups of atoms.

Molecular orbitals are obtained from the combination of atomic orbitals, which predict the location of an electron in an atom.

Molecular orbitals arise from allowed interactions between atomic orbitals, which are allowed if the symmetries ( determined from group theory ) of the atomic orbitals are compatible with each other.

Molecular orbitals were first introduced by Friedrich Hund and Robert S. Mulliken in 1927 and 1928.

Molecular orbitals are said to be degenerate if they have the same energy.

Molecular orbitals

Molecular orbitals require different quantum numbers, because the Hamiltonian and its symmetries are quite different.

Molecular fragments joined by a pi bond cannot rotate about that bond without breaking the pi bond, because rotation involves destroying the parallel orientation of the constituent p orbitals.

Molecular orbital ( MO ) theory uses a linear combination of atomic orbitals ( LCAO ) to represent molecular orbitals involving the whole molecule.

Molecular orbitals are further divided according to the types of atomic orbitals combining to form a bond.

His prize-winning work focused on the role of frontier orbitals in chemical reactions: specifically that molecules share loosely bonded electrons which occupy the frontier orbitals, that is the Highest Occupied Molecular Orbital ( HOMO ) and the Lowest Unoccupied Molecular Orbital ( LUMO ).

Molecular orbital scheme, illustrating the linear combination of P – R σ * and P 3d orbitals to form PR3 π acceptor orbitals

Molecular systems capable of shifting a chemical or mechanical process away from equilibrium represent a potentially important branch of chemistry and nanotechnology.

Molecular genetics study suggests that surviving Amerindian populations derived from a theoretical single founding population, possibly from only 50 to 70 genetic contributors Preliminary research, restricted to only 9 genomic regions ( or loci ) have shown a genetic link between original Americas and Asia populations.

* ( 2001 ): Molecular systematics of the Oncidiinae based on evidence from four DNA sequence regions: expanded circumscriptions of Cyrtochilum, Erycina, Otoglossum, and Trichocentrum and a new genus ( Orchidaceae ).

Molecular systematics of the Oncidiinae based on evidence from four DNA sequence regions: expanded circumscriptions of Cyrtochilum, Erycina, Otoglossum, and Trichocentrum and a new genus ( Orchidaceae ) in Lindleyana 16 ( 2 ): 113-139 .</ ref > The last common species which was occasionally classified under Miltonia is Chamaeleorchis warszewiczii ,< ref >< span style =" font-variant: small-caps "> Senghas, Karlheinz & Lückel, Emil </ span > ( 1997 ).

( ii ) Molecular configuration in the three regions marked in the-A curve ; ( a ) gaseous phase, ( b ) liquid-expanded phase, and ( c ) condensed phase.

Molecular bond energies are on the order of one eV per molecule.

* Molecular encapsulation, in chemistry, the confinement of an individual molecule within a larger molecule

Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H < sub > 2 </ sub > is CO ( carbon monoxide ).

Molecular scale electronics, also called single molecule electronics, is a branch of nanotechnology that uses single molecules, or nanoscale collections of single molecules, as electronic components.

Molecular excitons may even be entirely located on the same molecule, as in fullerenes.

Molecular excitons typically have characteristic lifetimes on the order of nanoseconds, after which the ground electronic state is restored and the molecule undergoes photon or phonon emission.

Molecular excitons have several interesting properties, one of which is energy transfer ( see Förster resonance energy transfer ) whereby if a molecular exciton has proper energetic matching to a second molecule's spectral absorbance, then an exciton may transfer ( hop ) from one molecule to another.

* Molecular shuttles, a molecule capable of nanoscale transportation

Molecular geometry refers to the spatial arrangement of atoms in a molecule and the chemical bonds that hold the atoms together.

Molecular hyperfine structure is generally dominated by these two effects, but also includes the energy associated with the interaction between the magnetic moments associated with different magnetic nuclei in a molecule, as well as between the nuclear magnetic moments and the magnetic field generated by the rotation of the molecule.

Molecular cloning of the Interleukin 1 Beta converting enzyme is generated by the proteolytic cleavage of an inactive precursor molecule.

Molecular mechanics or molecular dynamics are most often used to predict the conformation of the small molecule and to model conformational changes in the biological target that may occur when the small molecule binds to it.

The Molecular Libraries Screening Center Network or MLSCN performs HTS on assays provided by the research community, against a large library of small molecules maintained in a central molecule repository.

Molecular geometry or molecular structure is the three-dimensional arrangement of the atoms that constitute a molecule.

* Molecular knot: a molecule in the shape of a knot such as a trefoil knot.

Molecular electronic transitions take place when electrons in a molecule are excited from one energy level to a higher energy level.

It began in the 1948 paper, " On the Problem of the Molecular Theory of Superconductivity " where Fritz London proposed that the phenomenological London equations may be consequences of the coherence of a quantum state.

Other fields where chemical degrees are useful include Astrochemistry ( and Cosmochemistry ), Atmospheric chemistry, Chemical Engineering, Chemo-informatics, Electrochemistry, Environmental science, Forensic science, Geochemistry, Green chemistry, History of chemistry, Materials science, Medical science, Molecular Biology, Molecular genetics, Nanotechnology, Nuclear chemistry, Oenology, Organometallic chemistry, Petrochemistry, Pharmacology, Photochemistry, Phytochemistry, Polymer chemistry, Supramolecular chemistry and Surface chemistry.

DOE has awarded $ 22. 5 million over five years for PNNL ’ s new Center for Molecular Electrocatalysis, where scientists will study catalysts that covert electrical energy into chemical bonds and back again.

Molecular diagnostics using the mitochondrial DNA ( mtDNA ) cytochrome b gene can differentiate A. m. scutellata from other A. mellifera lineages, though mtDNA only allows one to detect an Africanized colony that has an Africanized queen, and not colonies where a European queen has mated with Africanized drones.

* Molecular vibrational mode, ν < sub > x </ sub > where x is the number of the vibration ( a label ).

* Molecular dynamics, a form of computer simulation where atoms and molecules are allowed to interact for a period of time under known laws of physics

Molecular dating, calibrated with geographic events in the absence of a good fossil record, points at the Late Miocene, c. 8 MYA, as the point where the two genera divided into their two respective lineages.

He received his Ph. D. in 1982 from Yale University's Department of Molecular Biophysics and Biochemistry, where he conducted research on X-ray scattering and protein structure.

Murad left his tenure at Stanford in 1988 for a position at Abbott Laboratories, where he served as a vice president until starting his own biotechnology company, the Molecular Geriatrics Corporation, in 1993.

In 1996 he moved to Rockefeller University as a professor and head of the Laboratory of Molecular Neurobiology and Biophysics where he started to work on the structure of the potassium channel.

In 1972 she was accepted into the Biochemistry and Molecular Biology training program offered by The Johns Hopkins University School of Medicine, where in 1978 she earned a Ph. D. degree.

In 1964, Dr. Fox moved to the University of Miami where he was a professor and the director of the Institute for Molecular Evolution for 25 years.

Bill Gates already had a considerable interest in biotechnology, both as a philanthropist and as an investor, and after meeting Hood, donated $ 12 million dollars to UW to enable him to head a new department of molecular biotechnology, where Hood continues to hold a faculty position as the Gates Professor of Molecular Biotechnology.

In 1972, he became director of the Unit of Molecular Neurobiology at the Pasteur Institute, where he received a professorship in 1975.

She is a Professor of Molecular Biology at Princeton University, where her laboratory studies molecular and genetic mechanisms in fruit fly ( Drosophila melanogaster ) oogenesis.

He is a faculty member at MIT's Department of Civil and Environmental Engineering, where he directs the Laboratory for Atomistic and Molecular Mechanics ( LAMM ).

Molecular docking can be thought of as a problem of “ lock-and-key ”, where one is interested in finding the correct relative orientation of the “ key ” which will open up the “ lock ” ( where on the surface of the lock is the key hole, which direction to turn the key after it is inserted, etc .).