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  2. Time-dependent density functional theory - Wikipedia

    en.wikipedia.org/wiki/Time-dependent_density...

    The RG theorem shows that, for a given initial wavefunction, there is a unique mapping between the time-dependent external potential of a system and its time-dependent density. This implies that the many-body wavefunction, depending upon 3 N variables, is equivalent to the density, which depends upon only 3, and that all properties of a system ...

  3. Density dependence - Wikipedia

    en.wikipedia.org/wiki/Density_dependence

    Density-dependent fecundity. Density-dependent fecundity exists, where the birth rate falls as competition increases. In the context of gastrointestinal nematodes, the weight of female Ascaris lumbricoides and its rates of egg production decrease as host infection intensity increases. Thus, the per-capita contribution of each worm to ...

  4. Density functional theory - Wikipedia

    en.wikipedia.org/wiki/Density_functional_theory

    Density functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-body systems, in particular atoms, molecules, and the condensed phases.

  5. Lotka–Volterra equations - Wikipedia

    en.wikipedia.org/wiki/Lotka–Volterra_equations

    The model was later extended to include density-dependent prey growth and a functional response of the form developed by C. S. Holling; a model that has become known as the Rosenzweig–MacArthur model. [21] Both the Lotka–Volterra and Rosenzweig–MacArthur models have been used to explain the dynamics of natural populations of predators and ...

  6. Solvent model - Wikipedia

    en.wikipedia.org/wiki/Solvent_model

    RISM allows the solvent density to fluctuate in a local environment, achieving a description of the solvent shell behaviour. [1] [2] [5] QM/MM methods enable a section of the system to be calculated using quantum mechanics, for example the active site in a biological molecule, whilst the rest of the system is modeled using MM force fields. By ...

  7. Density - Wikipedia

    en.wikipedia.org/wiki/Density

    Increasing the pressure always increases the density of a material. Increasing the temperature generally decreases the density, but there are notable exceptions to this generalization. For example, the density of water increases between its melting point at 0 °C and 4 °C; similar behavior is observed in silicon at low temperatures.

  8. Dependent and independent variables - Wikipedia

    en.wikipedia.org/wiki/Dependent_and_independent...

    [6] [7] It is possible to have multiple independent variables or multiple dependent variables. For instance, in multivariable calculus, one often encounters functions of the form z = f(x,y), where z is a dependent variable and x and y are independent variables. [8] Functions with multiple outputs are often referred to as vector-valued functions.

  9. Intensive and extensive properties - Wikipedia

    en.wikipedia.org/wiki/Intensive_and_extensive...

    For example, the mass of a sample is an extensive quantity; it depends on the amount of substance. The related intensive quantity is the density which is independent of the amount. The density of water is approximately 1g/mL whether you consider a drop of water or a swimming pool, but the mass is different in the two cases.