================================================ Ab initio phasing and chain tracing - ARCIMBOLDO ================================================ `ARCIMBOLDO `_ originally conceived for *ab initio* phasing of macromolecular structures. There are two main barriers for *ab initio* phasing: structure size and resolution of the data. **ARCIMBOLDO** constitutes a general method for 2 Å data, based on a combination of small α-helices with `Phaser <../phaser_pipeline/index.html>`_ ( to locate small model fragments) and `SHELXE <../shelx/shelx.html>`_ (density modification with and autotracing). Please, choose the ARCIMBOLDO program to run: `ARCIMBOLDO_LITE <./lite.html>`_ performs *ab initio* phasing using polyalanine helices or other single search fragments. (http://chango.ibmb.csic.es/) `ARCIMBOLDO BORGES <./borges.html>`_ performs ab initio phasing with nonspecific libraries of small folds. (http://chango.ibmb.csic.es/borges) `ARCIMBOLDO_SHREDDER <./shredder.html>`_ uses fragments derived from a distant homolog template. (http://chango.ibmb.csic.es/shredder) *Helical structures are preferable cases for phasing with ARCIMBOLDO* The program documentation for `ARCIMBOLDO_LITE <./lite.html>`_ , `ARCIMBOLDO BORGES <./borges.html>`_ and `ARCIMBOLDO_SHREDDER <./shredder.html>`_