Optimize Lindemann Index Calculation Using Distance Vector

[N720720]

🔈 Motivation

The initial implementation of the Lindemann index calculation utilized a square-form distance matrix. By switching to a distance vector, we save memory and enhance computational efficiency.

📝 Description of the Optimization

The optimization replaces the square-form distance matrix with a distance vector. This change reduces memory usage and improves computational performance. The distance vector requires $(n* \frac{(n-1)}{2} )$ storage space, compared to the $( n*n )$ space needed for a full distance matrix, where $( n )$ is the number of atoms.

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