Ab initio molecular dynamics simulation of H5O+2 and H7O+3 gas phase clusters based on density functional theory

Gas‐Phase Infrared Spectrum of the Protonated Water Dimer: Molecular Dynamics Simulation and Accuracy of the Potential Energy Surface

“…Analysis of the MD trajectories shows that these motions cannot be described by the asymmetric OÀH + ÀO stretching normal mode alone, but are also coupled to low-frequency reorientations of the terminal water molecules (torsion and wagging). This was documented in a previous MD study at the DFT level [18] and is also in agreement with the recent analysis of a fitted CCSD(T)/aug-cc-pVTZ PES. [9] These findings show that a low-dimensional quantum treatment which takes only modes of the O-H + -O unit into account, such as the previous (2 2)D model, [4] cannot reproduce all features of the broad band between 850 and 1300 cm…”

“…The spectrum is very similar to those previously obtained by MD on MP2 [4] or DFT PES. [18] The red spectrum was obtained by exciting selectively the asymmetric OÀ H + ÀO stretching mode, and the blue and green spectra by exciting selectively the OÀH + ÀO x,y mode. The smoother upper curve is the spectrum obtained by the maximum-entropy method [24] (200 poles).…”

Automated exploration of stable isomers of H+(H2O)n (n = 5–7) via ab initio calculations: An application of the anharmonic downward distortion following algorithm

“…The present search for the isomers of H 1 (H 2 O) 6 led to 24 minima, among which 10 most stable isomers in free-energy and potential energy with ZPE correction are shown in Figures 2a and 2b, respectively. As seen from Figure 2, the 6I with ''Zundel'' motif is the most stable with respect to both free energy (170 K; Fig.…”

“…At 6 , the HF/6-31G calculation is more computationally expensive than the HF/3-21G calculation. The higher computational level, such as B3LYP/ 6-311G**, for LADD-following process would certainly need more computational time.…”

Environmental effects on vibrational proton dynamics in H5O2+: DFT study on crystalline H5O2+ClO4−

“…For the isolated H 5 O 2 1 ion in the gas phase Born-Oppenheimer molecular dynamics simulations were made with DFT forces (AIMD) 21,22 using the TURBOMOLE package (V5-6) [23][24][25] The forces were calculated analytically using the BLYP functional 26 and the aug-cc-pVTZ basis set. 27 NVE simulations were performed such that the average of the kinetic energy corresponds to a temperature of about 100 K. The equilibrium structure was used as a starting point.…”