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  2. Atoms in molecules - Wikipedia

    en.wikipedia.org/wiki/Atoms_in_molecules

    In quantum chemistry, the quantum theory of atoms in molecules (QTAIM), sometimes referred to as atoms in molecules (AIM), is a model of molecular and condensed matter electronic systems (such as crystals) in which the principal objects of molecular structure - atoms and bonds - are natural expressions of a system's observable electron density distribution function.

  3. Hydrogen atom - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_atom

    Depiction of a hydrogen atom showing the diameter as about twice the Bohr model radius. (Image not to scale) A hydrogen atom is an atom of the chemical element hydrogen.The electrically neutral hydrogen atom contains a single positively charged proton in the nucleus, and a single negatively charged electron bound to the nucleus by the Coulomb force.

  4. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    The study of molecules by molecular physics and theoretical chemistry is largely based on quantum mechanics and is essential for the understanding of the chemical bond. The simplest of molecules is the hydrogen molecule-ion, H 2 +, and the simplest of all the chemical bonds is the one-electron bond.

  5. Dihydrogen cation - Wikipedia

    en.wikipedia.org/wiki/Dihydrogen_cation

    The dihydrogen cation or hydrogen molecular ion is a cation (positive ion) with formula +. It consists of two hydrogen nuclei , each sharing a single electron. It is the simplest molecular ion. The ion can be formed from the ionization of a neutral hydrogen molecule by

  6. Quantum chemistry - Wikipedia

    en.wikipedia.org/wiki/Quantum_chemistry

    Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions to physical and chemical properties of molecules, materials, and solutions at the atomic level. [1]

  7. Molecular Hamiltonian - Wikipedia

    en.wikipedia.org/wiki/Molecular_Hamiltonian

    Advanced Molecular Quantum Mechanics. Chapman and Hall. ISBN 978-0-412-10490-9. Tinkham, Michael (2003). Group Theory and Quantum Mechanics. Dover Publications. ISBN 978-0-486-43247-2. A readable and thorough discussion on the spin terms in the molecular Hamiltonian is in: McWeeny, R. (1989). Methods of Molecular Quantum Mechanics (2nd ed ...

  8. Quantum number - Wikipedia

    en.wikipedia.org/wiki/Quantum_number

    In quantum physics and chemistry, quantum numbers are quantities that characterize the possible states of the system. To fully specify the state of the electron in a hydrogen atom, four quantum numbers are needed. The traditional set of quantum numbers includes the principal, azimuthal, magnetic, and spin quantum numbers. To describe other ...

  9. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals. The ability of atoms to attach and detach from each other is responsible for most of the physical changes observed in nature. Chemistry is the science that studies these changes.