1. What is the Lennard-Jones Potential?

Definition: The Lennard-Jones potential describes the interaction between neutral atoms or molecules based on their distance.

Purpose: It's widely used in molecular dynamics simulations and computational chemistry to model van der Waals forces.

2. How Does the Calculator Work?

The calculator uses the Lennard-Jones potential formula:

Where:

• \( V \) — Potential energy (Joules)
• \( \epsilon \) — Depth of potential well (Joules)
• \( \sigma \) — Finite distance where potential is zero (meters)
• \( r \) — Distance between particles (meters)

Explanation: The first term represents Pauli repulsion at short ranges, while the second term represents London dispersion attraction.

3. Importance of Lennard-Jones Potential

Details: This potential is crucial for understanding molecular interactions, phase behavior, and material properties at the atomic scale.

4. Using the Calculator

Tips: Enter ε (typically 0.001-0.01 eV for noble gases), σ (atomic diameter scale), and r (distance between particles). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for ε and σ?
A: For argon: ε ≈ 0.0104 eV (1.67×10⁻²¹ J), σ ≈ 3.4 Å (3.4×10⁻¹⁰ m). Values vary by substance.

Q2: Why the 12-6 exponents?
A: The 12th power term approximates Pauli repulsion, while the 6th power term comes from London dispersion theory.

Q3: At what distance is the potential zero?
A: The potential is zero when r = σ, by definition of the σ parameter.

Q4: What's the equilibrium distance?
A: The minimum potential occurs at r = 2^(1/6)σ ≈ 1.122σ.

Q5: Can this be used for all molecules?
A: It works best for non-polar, spherical molecules. More complex potentials are needed for polar or asymmetric molecules.