NCIPLOT

Official Resources

• Homepage: https://github.com/aoterodelaroza/nciplot
• GitHub: https://github.com/aoterodelaroza/nciplot
• Documentation: Included in repository
• Publication: E. R. Johnson et al., J. Am. Chem. Soc. 132, 6498 (2010)
• License: GNU General Public License

Overview

NCIPLOT is a program that enables the computation and graphical visualization of inter- and intra-molecular non-covalent interactions (hydrogen bonds, π-π interactions, van der Waals contacts) using the reduced density gradient (RDG) method. It produces 3D isosurfaces that can be visualized with molecular graphics programs.

Scientific domain: Non-covalent interactions, hydrogen bonding, weak interactions Target user community: Researchers studying molecular recognition, supramolecular chemistry, and weak interactions

Theoretical Methods

• Reduced density gradient (RDG) analysis
• Electron density topology
• Sign(λ2)ρ coloring scheme
• Promolecular density approximation
• Self-consistent field density analysis

Capabilities (CRITICAL)

• NCI Visualization: 3D isosurfaces of non-covalent regions
• Hydrogen Bonds: Identification and visualization
• π-π Stacking: Aromatic interaction analysis
• Van der Waals: Weak dispersion contacts
• Promolecular Mode: Fast approximate analysis
• SCF Mode: Accurate DFT-based analysis
• Large Systems: Proteins and biomolecules

Sources: NCIPLOT documentation, JACS publication

Key Strengths

Visual Analysis:

• Intuitive 3D visualization
• Color-coded interaction strength
• VMD/PyMOL compatible output
• Publication-quality figures

Flexibility:

• Promolecular (fast) mode
• SCF (accurate) mode
• Cube file input
• Multiple output formats

Widely Validated:

• Extensively benchmarked
• High citation count
• Active development
• Critic2 integration

Inputs & Outputs

• Input formats:

  • Gaussian wfn/wfx files
  • Cube files (electron density)
  • XYZ coordinates (promolecular)

• Output data types:

  • Cube files for visualization
  • RDG isosurfaces
  • 2D RDG vs sign(λ2)ρ plots

Installation

git clone https://github.com/aoterodelaroza/nciplot.git
cd nciplot
make

Usage Examples

# Basic NCI analysis from wfn file
nciplot molecule.wfn

# Input file example (nciplot.nci):
molecule.wfn
# Output cube files for VMD visualization

Performance Characteristics

• Speed: Fast for promolecular, moderate for SCF
• Memory: Depends on grid resolution
• Scalability: Handles large biomolecules

Limitations & Known Constraints

• Visualization needed: Requires external viewer (VMD, PyMOL)
• Grid resolution: Trade-off with file size
• Qualitative: Primarily visual analysis tool
• Wavefunction required: SCF mode needs DFT output

Comparison with Other Tools

• vs Critic2: NCIPLOT specialized for NCI, Critic2 broader QTAIM
• vs Multiwfn: Both do NCI, different interfaces
• Unique strength: Focused NCI visualization, widely adopted

Application Areas

• Drug-receptor interactions
• Protein-ligand binding
• Crystal packing analysis
• Supramolecular chemistry
• Catalysis mechanisms

Best Practices

• Use promolecular for quick screening
• Use SCF for quantitative analysis
• Choose appropriate isosurface values
• Validate with other methods

Community and Support

• GitHub repository
• High-impact publication
• Developer: A. Otero-de-la-Roza
• Active maintenance

Verification & Sources

Primary sources:

1. GitHub: https://github.com/aoterodelaroza/nciplot
2. E. R. Johnson et al., J. Am. Chem. Soc. 132, 6498 (2010)
3. J. Contreras-García et al., J. Chem. Theory Comput. 7, 625 (2011)

Confidence: VERIFIED - Published in JACS

Verification status: ✅ VERIFIED

• GitHub repository: ACCESSIBLE
• Documentation: AVAILABLE
• Source code: OPEN (GPL)
• Academic citations: >4000
• Active development: Maintained