Madelung Constant Formula:
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Definition: The Madelung constant is used in determining the electrostatic potential of a single ion in a crystal by approximating the ions by point charges.
Purpose: It helps in calculating the lattice energy of ionic crystals and understanding their stability.
The calculator uses the formula:
Where:
Details: The Madelung constant is crucial for calculating lattice energies in ionic crystals and understanding their thermodynamic properties.
Tips: Enter the repulsive interaction constant, Born exponent (between 5-12), charge, and distance of closest approach. All values must be positive.
Q1: What is a typical value for the Madelung constant?
A: For common crystal structures, it ranges from ~1.6 for zincblende to ~1.75 for rocksalt structures.
Q2: Why is the Born exponent important?
A: It characterizes the repulsive potential between ions and affects the calculated Madelung constant.
Q3: How do I determine the repulsive interaction constant?
A: It's typically determined experimentally from compressibility measurements or theoretical calculations.
Q4: What units should I use?
A: Use SI units: meters for distance, Coulombs for charge, and J·mn for the repulsive constant.
Q5: Can this be used for any crystal structure?
A: This calculation is most accurate for simple ionic crystals with well-defined nearest-neighbor distances.