Papers

[2022 - ApJS - Quantum Mechanical Simulations of the Radical–Radical Chemistry on Icy Surfaces]
- The radical-radical coupling reactions are not always barrierless on icy surfaces. Each individual reaction should be evaluated individually.
- The switch from D3 to D3(BJ) would lead to different optimized structures of W18 and W33 even if the same functional is used.
- One of the limitation of this paper is that only one reaction site has been considered for the radical-radical reactions on W18 and W33 surfaces. (What is the most realistic way to describe reaction barriers on amorphous surfaces? Would one get a distribution of energy barriers instead of a single value? How to do that?)
- More realistic water cluster models other than W33 are needed in the future and MD will also be helpful to provide more insights into the reactions on icy surfaces.
[2021 - A&A Germán Molpeceres et al. Binding energies and sticking coefficients of H2 on crystalline and amorphous CO ice]
- ortho-para spin conversion in H2
- Quantities governing the fraction of molecules that return to the gas phase after a collision with an ice surface are sticking coefficients and residence times.
  - The sticking coefficient represents the fraction of molecules that remains adsorbed after a collision.
  - Residence times quantify the time that a particular adsorbate stays on a surface after adsorption.
- Sampling is based on GFN-FF simulations at 20K and 1000K with a Berendsen thermostat.
- BHLYP-D4 was chosen as the reference method because it offered good description of CO-CO and CO-H2 interactions compared with CCSD(T)-F12/cc-pVTZ-F12
- Rigid scan at different CO-H2 distances is used as the validation of neural network potentials
[2020 - ApJ - Herbert M. Urbassek et.al.]: Ejection of Glycine Molecules Adsorbed on a Water Ice Surface by Swift-heavy Ion Irradiation (MD-irradiation)
[2020 - PCCP - Germán Molpeceres and Johannes Kästner]: Adsorption of H2 on amorphous solid water studied with molecular dynamics simulations (QM/MM, GFN2-xTB)
- Sticking coefficients (from 0 to 1, fraction of molecules sticking on surface after a collision) of H2 depends on H2 kinetic energy and the surface temperature, hardly on the incident angle
- Methods for calculating sticking coefficients: analytical model, molecular dynamics (many studies on H, CO, few on H2)
- The surface of amorphous ice is simulated by taking a hemispherical clusters from 18937 water molecules in a periodic cubic cell.
[2020 - Nat Astro - Alexey Potapov et.al.]: Dust/ice mixing in cold regions and solid-state water in the diffuse interstellar medium
- A substantial fraction of solid water may be mixed with silicate dust grain in the diffuse ISM, protostellar envelopes and protoplanetary disks.
- The desorption temperature of water ice in laboratory is 160 - 180K, depending on the ice thickness and the heating rate.
- The strongest spectral variations can be seen in the 3.1 $\mu m$ (3225.8 cm $^{-1}$) water ice band which provides the cleanest measure of the H2O ice column density in the astrophysical environments.
- Mixing H2O IR spectra at 10K and 150K and comparing with observation is used for determining relative abundance of low-temperature ice and high-temperature ice
  - Mixing pure H2O spectra at 10K and 150K: more than 80% ice in protostellar envelopes and protoplanetary disk is low-temperature ice
  - Mixing the silicate/ice spectra at 10K and 150K: the low-temperature ice accounts for only about 30-50% of the column mass toward the investigated objects.
- The presence of solid-water in the diffuse medium (where water molecules could be embedded in silicates) is validated by matching 6.2 $\mu m$ water band in the laboratory 200K spectrum and the band in the Spitzer spectrum
[2016 - PCCP - Martin R. S. McCoustra et.al.]: Peeling the astronomical onion
[2014 - A&A - Combined quantum chemical and modeling study of CO hydrogenation on water ice]
- I assume that BHLYP (50 % HF) is the same as BHandHLYP
[2004 - J. Phys. Chem. A - Performance of Density Functionals for Calculating Barrier Heights of Chemical Reactions Relevant to Astrophysics]
- BHandHLYP has 50% HF

H2O

[2005 - J. Chem. Phys - IR spectrum of liquid water from MD simulation]
- A CP2k tutorial related with this can be found in cp2k-2015-exercise
[1994 - Science - Structural Transitions in Amorphous Water Ice and Astrophysical Implications]: its pdf version is available on zenodo.

CO2

[2022 - J. Chem. Phys - Vibrational relaxation of carbon dioxide in water]
[2017 - A&A - The profile of the bending mode band in solid CO2]
[2017 - J. Chem. Phys - Fermi resonance in CO2: Mode assignment and quantum nuclear effects from first principles molecular dynamics]
[2014 - J. Chem. Phys - Density functional theory for carbon dioxide crystal]
[1995 - PRB - Ab initio molecular dynamics in adaptive coordinates]: AIMD simulations on single CO2 molecule reproduce Fermi resonance.
[1989 - Comput. Phys. Commun. - Molecular dynamics study of liquid carbon monoxide]

A way to build CO2 crystal in ase is

## http://rruff.geo.arizona.edu/AMS/CIF_text_files/11286_cif.txt
from ase.spacegroup import crystal
a = 5.624
co2 = crystal(['C', 'O'], [(0, 0, 0), (0.1185, 0.1185, 0.1185)], spacegroup='Pa-3', cellpar=[a, a, a, 90, 90, 90])

Others

https://www.nature.com/articles/s41467-020-15377-8 vdW interactions are important to water adsorption on surfaces, but have minor effects on the binding geometries - zero-pressure-LAMMPS-1 - zero-pressure-LAMMPS-2

Talks

2020-06 - Sergio Ioppolo - Infrared Resonant Vibrationally Induced Restructuring of Amorphous Solid Water

What we want in experiments are intense lights with tunable frequencies. Pulses are needed as well