.. _before_getting_started: .. |check| raw:: html .. |uncheck| raw:: html Before getting started ====================== The following is a list of some requirements and recommendations to help prepare the 2D dataset for inversion. Common recommendations/requirements ''''''''''''''''''''''''''''''''''' .. list-table:: :widths: 2 98 * - |uncheck| - **Dataset shear** The inversion method assumes that the 2D dataset is sheared, such that one of the dimensions corresponds to a pure anisotropic spectrum. The anisotropic cross-sections are centered at 0 Hz. **Required**: Apply a shear transformation before proceeding. * - |uncheck| - **Calculate the noise standard deviation** Use the noise region of your spectrum to calculate the standard deviation of the noise. You will require this value when implementing cross-validation. Spinning Sideband correlation dataset specific recommendations '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' .. list-table:: :widths: 2 98 * - |uncheck| - **Data-repeat operation** A data-repeat operation on the time-domain signal corresponding to the sideband dimension makes the spinning sidebands look like a stick spectrum after a Fourier transformation, a visual, which most NMR spectroscopists are familiar from the 1D magic-angle spinning spectrum. Like a zero-fill operation, a spinning sideband data-repeat operation is purely cosmetic and adds no information. In terms of computation, however, a data-repeated spinning-sideband spectrum will take longer to solve. **Strongly recommended**: Avoid data-repeat operation. Magic angle flipping dataset specific recommendations ''''''''''''''''''''''''''''''''''''''''''''''''''''' .. list-table:: :widths: 2 98 * - |uncheck| - **Isotropic shift correction along the anisotropic dimension** Ordinarily, after shear, a MAF spectrum is a 2D isotropic *v.s.* pure anisotropic frequency correlation spectrum. In certain conditions, this is not true. In a MAF experiment, the sample holder (rotor) physically swaps between two angles (:math:`90^\circ \leftrightarrow 54.735^\circ`). It is possible to have a slightly different external magnetic fields at the two angles, in which case, there is an isotropic component along the anisotropic dimension, which is not removed by the shear transformation. **Required**: Correct for the isotropic offset along the anisotropic dimension by adding an appropriate coordinates-offset. * - |uncheck| - **Zero-fill operation** Zero filling the time domain dataset is purely cosmetic. It makes the spectrum look visually appealing, but adds no information, that is, a zero-filled dataset contains the same information as a non-zero filled dataset. In terms of computation, however, a zero-filled spectrum will take longer to solve. **Recommendation**: If zero-filled, try to keep the total number of points along the anisotropic dimension in the range of 120 - 150 points.