  Laser-induced alignment of particles and molecules was long envisioned to
support three-dimensional structure determination using single-particle imaging
with x-ray free-electron lasers [PRL 92, 198102 (2004)]. However, geometric
alignment of isolated macromolecules has not yet been demonstrated. Using
molecular modeling, we analyzed and demonstrated how the alignment of large
nanorods and proteins is possible with standard laser technology, and performed
a comprehensive analysis on the dependence of the degree of alignment on
molecular properties and experimental details. Calculations of the
polarizability anisotropy of about 150,000 proteins yielded a skew-normal
distribution with a location of 1.2, which reveals that most of these proteins
can be aligned using appropriate, realistic experimental parameters. Moreover,
we explored the dependence of the degree of alignment on experimental
parameters such as particle temperature and laser-pulse energy.
