Feature Summary of HyperNMR Release 1

The HyperNMR package has been integrated into the core of HyperChem. This package allows for the simulation of NMR spectra. An accurante semi-empirical tailored specifically to NMR allows rapid interactive computation of NMR shielding constants (chemical shifts) and coupling constants for molecules as large as proteins. Basedon a solution of the quantum mechanical coupled-Hartree-Fock equations rather than simple database lookup, this package allows full exploration of NMR parameters in any situation, such as a new or novel chemical environment where simple database interpolation is impossible.

When appropriate, the NMR parameters can be integrated into a spin Hamiltonian to predict and display the full one-dimensional NMR spectra. The spectra can be manipulated to add line widths so as to simulate experimental spectra.

For more information on our NMR module, click here.

This brochure describes the main features of HyperNMR, a software package for the a priori prediction of one-dimensional NMR spectra. HyperNMR can be used as a stand-alone program or in conjunction with HyperChem.

Product Overview

HyperNMR can load a molecular system using different file formats, including a Z-matrix format or the HIN format of HyperChem. Molecular systems can also be transferred directly into HyperNMR via Dynamic Data Exchange. from HyperChem. The molecular system can then be displayed using various rendering methods.

The subsequent NMR calculations occur in two sequential steps. The first step computes magnetic shielding and nuclear spin coupling constants for any selected nuclei of the molecular system, using a quantum mechanical description of the electronic structure. The second step calculates the frequencies and intensities of the NMR spectra from the results of step one (or from user-specified shieldings and couplings). The spectra are displayed graphically along with user-specified line widths. A variety of options for displaying the results of each of the two steps is available along with the ability to transfer the graphical spectra onto the Windows clipboard and into another application for incorporation into a manuscript.

HyperNMR uses two new semi-empirical SCF-MO methods, TNDO/1 and TNDO/2, to compute magnetic shielding and nuclear spin coupling constants. These methods use different parameters for atoms of the same atomic number but different chemical environments, i.e. atom "type", in order to improve the accuracy of semi-empirical methods. These typed neglect of differential overlap (TNDO) methods are capable of giving reliable NMR shielding and coupling constants. The first release of a parameter set greatly improves shielding results over earlier methods.

NMR Parameter Calculation

HyperNMR calculates magnetic shielding for those atoms in a molecular system assigned a nuclear spin. It uses the gauge invariant atomic orbital (GIAO) self-consistent-field (SCF) perturbation theory with an external magnetic field as the perturbation. Nuclear spin coupling constants are calculated by the same rigorous SCF perturbation theory but with the Fermi contact interaction of a nuclear spin as the perturbation. The algorithms implemented in HyperNMR greatly improve the computational time over earlier methods and offer a tool for predicting NMR parameters and spectra for molecules from small organic systems to proteins.

NMR Spectral Simulation

NMR spectra can be simulated by HyperNMR based on the computed chemical shifts and spin coupling constants of step one, or chemical shifts and spin coupling constants obtained from elsewhere. There is no fixed limit on the number of nuclei in the NMR simulation: the maximum practical number of nuclei depends only computer memory. HyperNMR simulates the NMR spectra for spin 1/2 protons, C13, N15, F19, and P31.

NMR Spectral Presentation

HyperNMR allows you flexibility in your graphical representation of NMR spectra:

TNDO Method

HyperNMR uses two new SCF-MO methods for computing the electronic properties of molecules. These two methods, TNDO/1 and TNDO/2, include features from both conventional semi-empirical quantum mechanical methods and molecular mechanics methods. They have shown great improvement in their chemical shift predictions compared to the conventional semi-empirical SCF-MO methods. Principally, they incorporate the molecular mechanics concept of atom "type" and parameters specialized to atom type into quantum mechanical calculations.

Molecular Rendering

Final Comments

HyperNMR brings significant new chemistry to the desktop in an easy to use form. It can be integrated closely with HyperChem when desired. HyperNMR is a product of Hypercube, Inc., specialists in scientific software for Windows and the developers of HyperChem.

We hope this technical brochure answers your questions concerning HyperNMR. Should you require more information or should you wish to arrange to purchase HyperNMR, please contact us.