Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Post-stishovite transition in hydrous aluminous SiO2   Lakshtanov et al. (2007) showed that incorporation of aluminum and some water
into SiO2 significantly reduces the post-stishovite transition pressure in
SiO2. This discovery suggested that the ferroelastic post-stishovite transition
in subducted MORB crust could be the source of reflectors/scatterers with low
shear velocities observed in the mid to upper lower mantle. A few years later,
a similar effect was observed in anhydrous Al-bearing silica. In this paper, we
show using first principles static calculations and molecular dynamics using
inter-atomic potentials that hydrogen bonds and hydrogen mobility play a
crucial role in lowering the post-stishovite transition pressure. A cooperative
redistribution of hydrogen atoms is the main mechanism responsible for the
transition pressure reduction in hydrous aluminous stishovite. The effect is
enhanced by increasing hydrogen concentration. This perspective suggests a
potential relationship between the depth of seismic scatterers and the water
content in stishovite.

29
The categories of this paper are: funct-an
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th