WinVB2000 2.0 released (November 21, 2007). This Windows version is based on VB2000 2.0, which has the following major enhancements: VB2000 Version 1.8(R3) released (May 31, 2007). This version is updated and compatable with the current version of GAMESS (March 2007).
VB2000 Version 1.8(R2) released (July 25, 2006). This version has the following major improvements.
  • Added spin-density calculation for VB wave function.
  • Added DIIS convergence control for VBSCF.
  • Enhanced multiple-VB structure calculations with dynamic VB orbitals.
  • Extensively revised and updated the VB2000 user manual.
  • Fixed VB(1) and one-atom VB bugs.
VB2000 Version 1.8(R1) released (Nov. 3, 2005). See what is new in this revision.
VB2000 Version 1.8 released (July 24, 2005). See the screen shots of VB2000 GUI and VB orbitals

What is VB2000?

VB2000 is an ab initio electronic structure package for performing modern Valence Bond (VB) calculations based on a highly efficient VB algorithm—the so called Algebrant Algorithm. It has also a general implementation of the Group Function (GF) Theory, in which a large molecule is described in terms of its constituent parts of physically identifiable "electron groups".  The combination of the efficient VB algorithm and the general implementation GF theory in VB2000 makes it a useful tool for the investigation of the nature of chemical systems.

VB2000 is distributed in different packages for different platforms and third party systems. It can be used as a stand-alone program, which does not need a third party program for integrals and Hartree-Fock MO calculations. The stand-alone program can be installed on Unix/Linux platforms or on Microsoft Windows. The Windows version (WinVB2000) also has a simple graphic user interface. The Unix/Linux version can also be used as a plug-in module for GAMESS and Gaussian. The current release of Windows version of GAMESS (WinGAMESS) has VB2000 fully integrated and GAMESS provides an option to access VB2000 module.

What is new in VB2000 version 1.8?
Features of VB2000
Modern ab initio VB Method

VB2000 can be used for very general VB calculations:

  • Multi-Structure VB (VB)
  • Spin-Coupled VB (SCVB)
  • Complete Active Space VB (CASVB)
  • VB with Localized Electron Pairs (GVB)
  • VB Configuration Interaction (VBCI)
  • VB calcualtion with dynamic VB orbitals (BOVB type calculation).

Hartree-Fock Molecular Orbital Theory

Hartree-Fock molecular orbitals are generated before any type of VB calculations.  The HF orbitals are then used for generating an initial approximation to group functions and their corresponding initial one-electron densities.

Pipek-Mezey Localization Method
The Pipek-Mezey (PM) method for localization of molecular orbitals (MOs) has been implemented.
Group Function (GF) Theory

The general form of the GF theory has been fully implemented in VB2000. In general, a molecular wave function is expressed as an antisymmetrized product of individual group functions.The CASSCF and GVB type of wave functions are the special cases in the GF framework.

Structure Weight Analysis

Three methods for structure weight analysis have been implemented, i.e. the Mulliken type (i.e. the Chirgwin-Coulson type), the Lowdin type, and the Hiberty type.

Energy Profile of Chemical Reactions

VB2000 provides a functionality for the automatic calculation of the energy profile of a chemical reaction along the reaction path guided by a few intermediate structures (such as reactant, transition state, and product etc.).

Spin Density of VB Wave Functions

Spin density calculation has been introduced in VB2000 version 1.8(R2).

Visualization of VB Orbitals

Visualization files can be created so that VB oribtals can be visualized with third party programs, such as VMD and Molekel.

Run VB2000 on WEB

Run Fully Featured Web Version
Manual of VB2000 version 1.8(R2)   in PDF format

Download VB2000

Download Link
License Application Form

Platforms Supported

Windows NT/2000/XP
Mac OS X

VB2000 References

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