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IQmol3 is a free, open-source molecular editor and visualization package. You can use it to build molecular structures, inspect structures and computed results, and prepare input files for Q-Chem. It does not perform quantum chemistry calculations on its own. Running those calculations requires a separate Q-Chem installation on a local or remote system that IQmol can reach.
What IQmol3 is, and what it is not
IQmol is a molecular builder and visualization environment. The project describes it as a free, open-source molecular editor and visualization package, built on Qt for cross-platform use, with integration for Q-Chem (iqmol.org). The IQmol3 repository describes the same role: building molecules, setting up and submitting Q-Chem inputs, and analyzing output through molecular surfaces and animations (IQmol3 on GitHub).
The distinction matters. IQmol handles the drawing, file handling, input preparation, and display of results. The electronic-structure engine is Q-Chem, which is a separate package. If you only need to draw a molecule, clean up its geometry with the built-in force-field optimization, or view a file someone else produced, you do not need Q-Chem. If you want new energies, orbitals, or frequencies calculated, you do.
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Build and edit structures
The user guide describes a free-form builder for creating structures, a molecular mechanics force-field optimization, symmetry tools, and a library of molecules and functional groups (IQmol User Guide). These are the features most useful when you need a starting geometry before any quantum calculation.
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Inspect computed data
According to the same guide, IQmol displays atomic charges, dipole moments, normal modes, molecular orbitals, spin densities, van der Waals surfaces, and electrostatic-potential coloring. These are capabilities the guide documents. The guide does not present them as test results, so check them against your own files and your IQmol version before relying on a specific display option.
Animate vibrations and pathways
IQmol can animate vibrational modes and reaction or optimization pathways. This is useful for checking whether a normal mode looks physically sensible or whether an optimization moved the atoms the way you expected.
Supported platforms and file formats
The user guide lists Windows, Mac OS X, and Linux. Treat that list as the platforms the guide covers, not a guarantee for every current OS release. Mac OS X is the name the guide uses; check your own operating system version against the current download notes.
Rank #2
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 444 Pcs Complete Set: The atom model kit includes with 136 atoms,158 bonds, and 150 fullerene model parts, explore most the molecules structures from simple compounds to complex polymers.
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The guide names these formats:
- XYZ
- CML
- PDB
- MOL
- Formatted checkpoint (fchk)
- Cube
- Q-Chem input and output files
The guide does not say that every variant of each format will read correctly. If a file comes from a different program or an unusual writer version, open a test copy first and check atom count, coordinates, and charge or spin before trusting the display.
How IQmol relates to Q-Chem
The guide describes IQmol as usable on its own and designed to work with Q-Chem. Its Q-Chem User Interface organizes calculation options and generates the files that are submitted to a local or remote server where Q-Chem is installed. A typical workflow looks like this:
- Build or import the molecular structure in IQmol.
- Open the Q-Chem User Interface and set the calculation options you need.
- Generate the Q-Chem input files.
- Submit them to a machine where Q-Chem is installed, either on your own computer or on a remote server you can access.
- Load the Q-Chem output back into IQmol to inspect orbitals, charges, frequencies, and pathways.
Each step depends on the one before it. If Q-Chem is not installed on the target system, IQmol can still prepare input, but nothing will run it. For the menu labels and exact submission settings, use the guide’s Q-Chem section, since these change between versions.
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Installing IQmol3
Use a binary build
The project site links to a downloads page for binaries. Choose the build for your operating system from that page rather than the version in a third-party repository, unless you are on a distribution that packages IQmol for you. The project site is the right starting point for the current download (iqmol.org).
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Build from source
The source is hosted on GitHub. Its build notes have three requirements:
- The repository relies on git submodules, so clone it with submodules initialized (git’s
--recursiveoption), or the build will be missing code. - Qt must be installed and discoverable by CMake. Point
CMAKE_PREFIX_PATHat your Qt installation if CMake cannot find it on its own. - The build uses the project’s configure script followed by make.
Follow the repository’s current build notes for the exact configure options, since they can change between releases. If configuration fails, check first that CMake is locating the Qt version the project expects, then that the submodules are populated.
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Version and license context
The IQmol3 repository is labeled GPL-3.0 on GitHub. A Fedora package record lists IQmol 3.2.2 for Fedora 45 (package release 3.fc45) and gives the license as a combination of BSD-3-Clause, GPL-2.0-or-later, and GPL-3.0-or-later identifiers. That is packaging metadata for one distribution. It does not mean every upstream component carries the same license, so check the license files in the source you download if you plan to redistribute it.
For the current release, the project download page is the authoritative source. Older announcements on the project site may refer to earlier versions.
Feature history: check the version before you rely on it
The project’s features page keeps a versioned history of capabilities. It includes localized orbitals, excited-state densities and orbitals, Freezing String setup and analysis, POV-Ray scene export, clipping planes, spectra export, remote submission support, and support for multiple molecular formats (IQmol Features). These are historical entries, not a list of what the version you just installed includes. Before you plan a workflow around one of them, confirm the version that introduced it on that page.
Best Value
- Visualize Molecular: The molecular model kit simplifies complex chemistry concepts into tangible 3D structures improve learning efficiency, suitable for students from Grade 7 to Graduate level.
- 240 Pcs Complete Set: The atom model kit includes with 86 atoms and 154 bonds, explore most the molecules structures from simple compounds to complex polymers.
- Effortless Assembly: Embedded component design ensures easy to construct Ball-and-stick and Space-filling models that maximizes focus on exploration without complex assembly.
- Durable & Portable: Built to last, the chemistry set is crafted from high-quality materials. Plus, its portable design allows you to take your experiments learning anywhere, between the home, classroom and lab.
- Essential Study Tool: Whether you're studying organic chemistry, biochemistry, or molecular biology, molecule building kit is an perfect learning tool for you deeper comprehension of molecular science.
The guide’s public calculation server
The user guide describes a public calculation server with an approximate 10-minute limit. That description comes from an older edition of the guide, and its availability today is not established. Do not plan a workflow around it. For calculations you need to run now, use a Q-Chem installation you control, either locally or on a server your institution or company provides.
Choosing your setup
Before you install anything, answer these questions:
- Do you need to run calculations, or only to build and view results? Building and viewing need only IQmol. Running calculations also needs Q-Chem on a reachable system.
- Which formats do your files use? Check that each one is in the guide’s list, and test a copy of a real file.
- What do you need to see? Structures, surfaces, atomic properties, or animations each rely on the same application, but the input files you generate and load must contain the relevant data.
- What operating system will you use? Use the platform list in the guide, then check the current download page for your version.
- Is Q-Chem already available where your calculations will run? If not, install or arrange access to it before you set up submission.
- Do you need the newest features? Compare your version against the features history, or build from the current source.
If you answer that you only need to draw, check, and view structures on your own computer, a binary build from the project site is the simplest path. If you need Q-Chem calculations, plan the Q-Chem installation and submission target first, then set up IQmol around it.
Please note that IQmol is software only; no separate physical equipment or manual is required to use it.
IQmol’s documentation lives in the user guide PDF, and the source is at the IQmol3 repository.
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