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Effective Core Potential

Calvin Raab

Effective core potentials, also known as pseudopotentials, are a way of reducing the computational cost of quantum chemistry calculations and including relativistic corrections for heavy atoms. In this method, the explicit Coulombic interaction of the valence electrons with the nucleus and the core electrons is replaced by a screened pseudopotential.

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Electron Density

Van Do

Electron density refers to the probability of finding an electron at a certain point in space. In quantum mechanics, the uncertainty principle describes a constraint on an exact simultaneous measurement of the electron’s position and momentum. This means that the position of the electron can only be represented statistically through a probability.

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Entropy

Dylan Bian

Entropy is a fundamental concept in thermodynamics that measures the degree of disorder or randomness in a system. It indicates the amount of energy that is unavailable for useful work during a thermodynamic process. As the thermal energy of a system disperses and becomes less organized, the entropy of the system increases. In an isolated systems, it will inevitably arrive at a state of thermodynamic balance, where entropy is at its maximum, and therefore, cannot decrease over time. Hence, entropy is also regarded as a measure of the system’s disorder. It is a critical concept in understanding energy transformations and the efficiency of energy systems.

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Exchange-Correlation Functional

Scott I. Kaiser

Within the context of Kohn-Sham Density Functional Theory, the exchange-correlation (xc) functional is a term in the electronic potential that captures the portion of the energy which cannot be described by Coulombic effects and classical (Hartree) electron-electron interactions. As such, the xc functional is the portion of the DFT potential that captures all of the complex effects arising from the phenomena of electron exchange and correlation.

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