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Difference density ​

An Fo−Fc difference map calculated entirely in the browser: the urea sample CIF embeds its observed reflections (SHELX HKL data), so CifVis fits a scale, computes IAM structure factors, applies extinction correction, and displays the map progressively — no pre-computed map file involved. Use the density button (top right, appears once calculation starts) to hide/show the map. Typical applications: supplementary material for papers, refinement quality checks, teaching Fourier maps.

Reproduce it ​

html
<cifview-widget
    src="coordinates-and-reflections.cif"
    options='{"differenceDensity":{"autoLoad":true}}'>
</cifview-widget>
js
import { CrystalViewer } from 'cifvis';

const viewer = new CrystalViewer(container, {
    differenceDensity: { autoLoad: true },
});
const loaded = await viewer.loadCIF(cifText);
// The structure renders immediately; density finishes asynchronously.
await loaded.differenceDensity;

// Tune the display afterwards without recalculating:
viewer.updateIsosurfaceOptions({ sigmaLevel: 2.5, wireframe: true });

Explicit FCF files work the same way via viewer.loadDifferenceDensity(fcfText, 0, options), and pre-calculated grids via viewer.loadCube(cubeText, options) — see Library → Density maps.