# Geometrical Descriptors Plugin

This manual gives you a walk-through on how to use the Geometrical Descriptors Plugin:

# Introduction

The Geometrical Descriptors Plugin calculates 3D geometric descriptors for a molecule. The following window shows a calculation result.

Fig.1 Geometrical Descriptors Plugin result window

# Options

The following options can be set in the* **Geometrical Descriptors Options* window:

**Type****Dreiding energy:**calculates the energy of the 3D structure (conformation) of the molecule using Dreiding force field.**MMFF94 energy:**calculates the energy of the 3D structure (conformation) of the molecule using MMFF94 force field.**Steric hindrance:**calculates steric hindrance of an atom calculated from the covalent radii values and geometrical distances.**Minimal projection area:**calculates the minimum of projection areas of the conformer, based on the van der Waals radius (in Å^{2}).**Maximal projection area:**calculates the maximum of projection areas of the conformer, based on the van der Waals radius (in Å^{2}).**Minimal projection radius:**calculates the radius for the minimal projection area of the conformer (in Å).**Maximal projection radius:**calculates the radius for the maximal projection area of the conformer (in Å).**Maximal distance perpendicular to the min projection:**calculates the maximal extension of the conformer perpendicular to the minimal projection area (in Å).**Maximal distance perpendicular to the max projection:**calculates the maximal extension of the conformer perpendicular to the maximal projection area (in Å).**van der Waals volume:**calculates the van der Waals volume of the conformer (in Å^{3}).

**Energy unit:**unit of the calculated energy (kcal/mol or kJ/mol).**Decimal places:**setting the number of decimal places with which the result value is given.**Set MMFF94 optimalization**: The structure is optimized before MMFF94 energy calculation.**Set projection optimalization**The structure is optimized before projection area and projection radius calculation(s).**Calculate for lowest energy conformer:****If molecule is in 2D**: the lowest energy conformer is generated if the input molecule is in 2D; 3D input molecules are considered in the given conformation.**Never**: the input molecule is used for calculation.**Always**: the lowest energy conformer is generated (for 3D and 2D molecules as well).

**Optimization limit:**sets the rigour of convergence for optimization. Stricter convergence means lower gradient limit to reach during optimization. The values can be:Very loose

Normal

Strict

Very strict

Fig. 2 Geometrical Descriptors Options window