# Difference between revisions of "Gparse.m"

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− | # Gaussian prints all anisotropic quantities relative to what it calls "standard | + | # Gaussian prints all anisotropic quantities relative to what it calls "standard orientation". Do not use the "input orientation", that would be wrong. |

+ | # Do not instruct Gaussian to print eigenvectors of shielding tensors (nmr=printeigenvectors): that option has a bug that makes the eigenvectors refer to the symmetric part of the shielding tensor. Eigenvectors are not necessary anyway - the relevant orientation information is already contained in the shielding tensor matrix. | ||

# Chemical shielding is ''not'' the same as chemical shift. | # Chemical shielding is ''not'' the same as chemical shift. | ||

# Spin-rotation tensors are imported, but not used anywhere in ''Spinach'' at the moment. | # Spin-rotation tensors are imported, but not used anywhere in ''Spinach'' at the moment. |

## Latest revision as of 11:27, 16 January 2020

A parser for Gaussian03 and Gaussian09 calculation logs. The function extracts all potentially useful information from the Gaussian log. The following sections must be added to the route section of the Gaussian03/9 input file to produce a useful log:

#p nmr=(giao,spinspin,susceptibility) output=pickett

Examples of complete Gaussian input files that perform geometry optimisation followed by magnetic properties calculations may be downloaded here, here, and here. Some real-life Gaussian logs that may be used for practice with data import are given in examples/standard_systems directory.

## Contents

## Syntax

props=gparse(filename,options)

## Arguments

filename - the name of the file to be parsed, a character string options - a cell array of character strongs, the following: 'g_nosymm' - turns off g-tensor symmetrisation 'cst_nosymm' - turns off shielding tensor symmetrisation 'hfc_nosymm' - turns off hyperfine tensor symmetrisation

## Returns

The following output fields are returned, *if the corresponding information is present in the log file*:

props.inp_geom - input geometry, natoms x 3 array, Angstrom props.std_geom - standard geometry, natoms x 3 array, Angstrom props.natoms - number of atoms, an integer props.method - model chemistry Gaussian had used, e.g. 'B3LYP' props.energy - SCF energy, Hartree props.hfc.iso - isotropic hyperfine couplings, natoms x 1 array, Gauss props.hfc.full.eigvals - HFC eigenvalues, natoms x 1 cell array of 3-vectors, Gauss props.hfc.full.eigvecs - HFC eigenvectors, natoms x 1 cell array of 3x3 matrices props.hfc.full.matrix - HFC tensors, natoms x 1 cell array of 3x3 matrices, Gauss props.g_tensor.eigvecs - g-tensor eigenvectors, 3x3 matrix props.g_tensor.eigvals - g-tensor eigenvalues, 3-vector, Bohr magneton units props.g_tensor.matrix - g-tensor, 3x3 matrix, Bohr magneton units props.cst - absolute shielding tensors, natoms x 1 cell array of 3x3 matrices, ppm relative to bare nucleus in vacuum props.j_couplings - isotropic J-couplings, nspins x nspins matrix, Hz props.srt - spin-rotation tensor, nspins x 1 cell array of 3x3 matrices, Hz props.nqi - nuclear quadrupole interaction tensors, nspins x 1 cell array of 3x3 matrices, Hz props.chi - magnetic susceptibility tensor, 3x3 matrix, cubic Angstroms props.gibbs - Gibbs free energy, Hartree props.symbols - atomic symbols, nspins x 1 cell array of character strings props.atomic_numbers - atomic numbers, nspins x 1 array of integers props.filename - log file name, a character string props.error - set to 1 if the log contains an error message

## Examples

A typical example of a Spinach input that uses data import from a Gaussian log appears below.

% Read the spin system properties (vacuum DFT calculation) options.min_j=1.0; [sys,inter]=g2spinach(gparse('../standard_systems/sucrose.log'),{ {'H','1H'} },31.8,options); % Magnet field sys.magnet=14.1; % Basis set bas.formalism='sphten-liouv'; bas.approximation='IK-2'; bas.connectivity='scalar_couplings'; bas.space_level=2; % Relaxation theory parameters inter.relaxation={'redfield'}; inter.rlx_keep='secular'; inter.tau_c=1e-9; % Spinach housekeeping spin_system=create(sys,inter); spin_system=basis(spin_system,bas); % Sequence parameters parameters.spins={'1H'}; parameters.rho0=state(spin_system,'L+','1H','cheap'); parameters.coil=state(spin_system,'L+','1H','cheap'); parameters.decouple={}; parameters.offset=1800; parameters.sweep=5000; parameters.npoints=8192; parameters.zerofill=65536; parameters.axis_units='ppm'; parameters.invert_axis=1; % Simulation fid=liquid(spin_system,@acquire,parameters,'nmr'); % Apodization fid=apodization(fid,'crisp-1d'); % Fourier transform spectrum=fftshift(fft(fid,parameters.zerofill)); % Plotting plot_1d(spin_system,real(spectrum),parameters);

**Further examples of Gaussian inputs:** gaussian_a.txt, gaussian_b.txt, gaussian_c.txt - note that the extra printing flag (#p) should always be present.

## Notes

- Gaussian prints all anisotropic quantities relative to what it calls "standard orientation". Do not use the "input orientation", that would be wrong.
- Do not instruct Gaussian to print eigenvectors of shielding tensors (nmr=printeigenvectors): that option has a bug that makes the eigenvectors refer to the symmetric part of the shielding tensor. Eigenvectors are not necessary anyway - the relevant orientation information is already contained in the shielding tensor matrix.
- Chemical shielding is
*not*the same as chemical shift. - Spin-rotation tensors are imported, but not used anywhere in
*Spinach*at the moment. - Hyperfine tensors are imported in Gauss because Gauss units do not depend on the electron g-tensor.
- This function parses Gaussian logs. Use g2spinach.m to convert that information into
*Spinach*input structures. - The parser is a bit old-school. If you are proficient with regular expressoins, we would really appreciate a hand.

## See also

oparse.m, g2spinach.m, cst_display.m, hfc_display.m, molplot.m

*Version 2.2, authors: Ilya Kuprov, Gareth Charnock, Jennifer Handsel*