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Molecular orbital
A molecular orbital is a one-electron wavefunction describing an electron in the effective field of the nuclei and other electrons of a molecule, usually built from atomic orbitals.
Molecular orbital diagram
A molecular orbital diagram, or MO diagram, is an energy-level chart showing how atomic orbitals combine into bonding and antibonding molecular orbitals, from which bond order follows.
Molecular orbital method
The molecular orbital method is a quantum chemical technique that represents a molecule's electrons as occupying orbitals built from atomic orbitals, computing energies, geometries, and vibrational frequencies.
Molecular orbital theory
Molecular orbital theory, also called the molecular orbital model, is the quantum-mechanical description of chemical bonding in which electrons occupy orbitals delocalized over the molecule.
Molecular orbital tomography
Molecular orbital tomography experimentally reconstructs the spatial shape of a molecule's orbitals, first demonstrated in 2004 on nitrogen and extended in 2009 by photoemission on surface-bound molecules.
Molecular oxygen
Molecular oxygen (dioxygen, O₂) is the diatomic molecule of two oxygen atoms, the life-supporting gas that makes up just under 21 percent of Earth's atmosphere and is paramagnetic.
Molecular quantum computing
Molecular quantum computing is an approach that uses ultracold polar molecules as qubits, growing from David DeMille's 2002 proposal and exploiting molecules' rich internal structure and strong dipole interactions.
Molecular qubits
Molecular qubits are quantum bits encoded in the internal states of molecules, most commonly rotational, hyperfine, or spin states, combining long-lived energy levels, tunable dipole interactions, and designable structure.
Molecular ratchet
A molecular ratchet, also called a Brownian motor, is a chemical mechanism that converts random thermal motion into directional movement, powering synthetic molecular motors and biomolecular machines like ATP-driven motor proteins.
Molecular recognition
Molecular recognition is the selective binding of a substrate by a molecular receptor, a pillar of supramolecular chemistry whose founders shared the 1987 Nobel Prize in Chemistry.
Molecular replacement
Molecular replacement is a crystallographic phasing method that estimates diffraction phases for a new protein structure from a related molecule's known structure, solving most structures today.
Molecular robot for sequence-specific peptide synthesis
A rotaxane-based artificial molecular machine built by David A. Leigh's group at the University of Manchester, first reported in Science in 2013, which assembles a peptide of a single programmed sequence.
Molecular self-assembly
Molecular self-assembly is the spontaneous association of molecules into stable, well-defined aggregates via weak noncovalent bonds, a bottom-up method for making 1 to 100 nanometer structures.
Molecular shuttle
A molecular shuttle is an interlocked assembly in which a macrocyclic ring moves between two recognition sites on a dumbbell-shaped axle, first characterized in solution in 1991.
Molecular states in beryllium-12
Molecular states in Beryllium-12 ($ ext{^{12}} ext{Be}$) are excited nuclear configurations of the isotope that feature two alpha particles bound by four valence neutrons in molecular-like orbitals.
Molecular Structure
Molecular structure: the 3D arrangement of atoms in a molecule, determined by X-ray diffraction, NMR, and computational methods such as DFT, and encoded for machine learning as SMILES, descriptors, or graphs.
Molecular structure and bonding of carbon dioxide
Carbon dioxide is a linear triatomic molecule, O=C=O, with two equal C=O double bonds of 116 pm, D∞h symmetry, zero dipole moment, and three vibrational fundamentals.
Molecular switch
A molecular switch is a molecule toggled reversibly between stable states by light, voltage, pH, or force; in a solid-state junction, the states differ in electrical conductance.
Molecular symmetry
Molecular symmetry is the set of spatial operations, such as rotations, reflections, and inversion, that leave a molecule unchanged; its point groups predict polarity, chirality, and spectra.
Molecular tweezers
Molecular tweezers are artificial host molecules with two binding arms, or pincers, joined by a spacer to grip guest molecules, a term introduced by Chen and Whitlock in 1978.
Molecular vibration
A molecular vibration is an oscillatory motion of a molecule's atoms about their equilibrium positions, absorbing infrared light at characteristic frequencies that serve as molecular fingerprints.
Molecular walker
A molecular walker is a molecule or assembly that moves along a track by sequentially binding and releasing feet, keeping at least one foot attached at all times.
Molecular water oxidation catalysis
Molecular water oxidation catalysis is the study of soluble metal complexes that accelerate water oxidation to oxygen, the four-electron bottleneck of artificial photosynthesis and water splitting.
Molecular weaving
Molecular weaving is the regular entanglement of flexible molecular strands into 2D fabrics or 3D networks with long-range order, the nanoscale counterpart of textile weaving.
Molecular-frame photoelectron angular distribution
The molecular-frame photoelectron angular distribution (MFPAD) describes photoelectron emission in coordinates fixed to the molecule, avoiding orientation averaging and probing photoionization dynamics, bond lengths, and emission time delays.
Molecularly imprinted solid phase extraction
Molecularly imprinted solid phase extraction (MISPE) is a sample preparation technique using synthetic polymers with template-shaped cavities to selectively extract trace analytes from complex samples before chromatographic analysis.
Molecule
A molecule is an electrically neutral group of more than one atom held together by covalent chemical bonds, a discrete unit distinct from the extended lattices of ionic compounds.
MoleculeNet
MoleculeNet is a benchmark suite for molecular machine learning, introduced in 2017 by the Pande Lab at Stanford. It curates 17 public datasets with standard metrics and splits, distributed through the DeepChem library.
MOLLER experiment
The MOLLER experiment, under construction in Jefferson Laboratory's Hall A in Virginia, will measure the weak charge of the electron via parity-violating Møller scattering with part-per-billion precision.
Møller–Plesset perturbation theory
Møller–Plesset perturbation theory is a quantum chemistry method that improves on Hartree–Fock by adding electron correlation through perturbation theory, introduced by Møller and Plesset in 1934.