# Kpcs.m

Computes pseudocontact shifts using the PDE method.

## Syntax

[pcs_vals,pcs_cube]=kpcs(probden,chi,ranges,nxyz,method)

## Description

Computes the three-dimensional distribution of pseudocontact shift field by solving Kuprov-Charnock equation for PCS. For further information on the equations and algorithms used in this function see http://dx.doi.org/10.1039/C4CP03106G

## Arguments

probden - paramagnetic centre probability density cube. chi - electron magnetic susceptibility tensor in cubic Angstroms. ranges - Cartesian axis extents for the electron spin density cube as [xmin xmax ymin ymax zmin zmax] in angstroms. nxyz - nuclear coordinates as [x y z] with multiple rows) at which PCS is to be evaluated, in Angstroms. method - 'fft' for Fourier transfrom solver (recommended), 'fdiff' for a finite difference solver.

## Returns

pcs_vals - pseudocontact shift in ppm at each nucleus. pcs_cube - pseudocontact shift field on the same grid as the spin density supplied.

## Examples

See the pseudocontact shift analysis tutorial and the examples in nmr_paramag directory of the standard example set supplied with *Spinach*.

## Notes

Minimal three-point schemes are used for the finite difference operators. Increase stencil size in the source code if you have enough memory. Beware of the periodic boundary condition effects - leave enough space on all sides of your paramagnetic centre probability density for the wraparound PCS to become negligible.

## See also

ppcs.m, ipcs.m, ippcs.m, ilpcs.m, lpcs.m

*Version 1.9, authors: Elizaveta Suturina, Gareth Charnock, Ilya Kuprov*