The B̃1A1 ← X̃1A1 absorption spectra of propargyl cations H2C3H+ and D2C3D+ were simulated by an efficient two-dimensional (2D) quantum model, which includes the C-C stretch (v5) and the C≡C stretch (v3) vibrational modes.  https://www.selleckchem.com/products/Temsirolimus.html  The choice of two modes was based on a scheme that can identify the active modes quantitively by examining the normal coordinate displacements (∆Q) directly based on the ab initio equilibrium geometries and frequencies of the X̃1A1 and B̃1A1 states of H2C3H+. The spectrum calculated by the 2D model was found to be very close to those calculated by all the higher three-dimensional (3D) quantum models (including v5, v3, and another one in 12 modes of H2C3H+), which validates the 2D model. The calculated B̃1A1 ← X̃1A1 absorption spectra of both H2C3H+ and D2C3D+ are in fairly good agreement with experimental results.The fundamental vibrational frequency of the B-N stretch in BH3NH3 has eluded gas-phase experimental observation for decades. This work offers a theoretical anharmonic prediction of this mode to be 644 cm-1, using a Cartesian quartic force field at the CCSD(T)-F12/cc-pVTZ-F12 level of theory. The other fundamental frequencies reported herein have a mean absolute error of only 5 cm-1 from the seven available gas-phase experimental frequencies, making the anharmonic vibrational frequencies and rotational constants the most accurate computational data available for BH3NH3 to date. The inclusion of Fermi, Coriolis, and Darling-Dennison resonances is a major source of this accuracy, with the non-resonance-corrected frequencies having a mean absolute error of 10 cm-1. In particular, the inclusion of the 2ν6 = ν5 type 1 Fermi resonance increases the B-N stretching frequency by 14 cm-1 compared to previous work. Ammonia borane also represents one of the largest molecules ever studied by quartic force fields, making this work an important step in extending the breadth of application for these theoretical rovibrational techniques.The Adam-Gibbs (AG) model, linking thermodynamics with molecular dynamics of glass-forming liquids, plays a crucial role in the studies of the glass transition phenomenon. We employ this approach to investigate the relationship between ion dynamics and thermodynamics in three imidazolium-based ionic liquids in the current work. We show that the AG relation, -log10σdc ∝ (TSc)-1 (where σdc, T, and Sc denote the dc-conductivity, absolute temperature, and configurational entropy, respectively), does not work when the whole supercooled liquid state is considered. Meanwhile, a linear relationship between -log10σdc and (TSe)-1 (where Se denotes the excess entropy) was observed in the entire supercooled range. On the other hand, the generalized AG model log10σdc ∝ (TScα)-1 with an additional free parameter α successfully describes the relation between σdc and Sc. The determined α values being less than unity indicate that the configurational entropy is insufficient to govern the ion dynamics. Meanwhile, we found a systematical decrease in α with the elongation of the alkyl chain attached to the imidazolium ring.The Hartree-Fock problem provides the conceptual and mathematical underpinning of a large portion of quantum chemistry. As efforts in quantum technology aim to enhance computational chemistry algorithms, the Hartree-Fock method, central to many other numerical approaches, is a natural target for quantum enhanced algorithms. While quantum computers and quantum simulation offer many prospects for the future of modern chemistry, the non-deterministic polynomial-complete Hartree-Fock problem is not a likely candidate. We highlight this fact from a number of perspectives including computational complexity, practical examples, and the full characterization of energy landscapes for simple systems.We investigate multiple photon-assisted Landau-Zener (LZ) transitions in a hybrid circuit quantum electrodynamics device in which each of two interacting transmission-line resonators is coupled to a qubit, and the qubits are driven by periodic driving fields and also coupled to a common phonon mode. The quantum state of the entire composite system is modeled using the multi-D2Ansatz in combination with the time-dependent Dirac-Frenkel variational principle. Applying a sinusoidal driving field to one of the qubits, this device is an ideal platform to study the photon-assisted LZ transitions by comparing the dynamics of the two qubits. A series of interfering photon-assisted LZ transitions takes place if the photon frequency is much smaller than the driving amplitude. Once the two energy scales are comparable, independent LZ transitions arise and a transition pathway is revealed using an energy diagram. It is found that both adiabatic and nonadiabatic transitions are involved in the dynamics. Used to model environmental effects on the LZ transitions, the common phonon mode coupled to the qubits allows for more available states to facilitate the LZ transitions. An analytical formula is obtained to estimate the short time phonon population and produces results in reasonable agreement with numerical calculations. Equipped with the knowledge of the photon-assisted LZ transitions in the system, we can precisely manipulate the qubit state and successfully generate the qubit dynamics with a square-wave pattern by applying driving fields to both qubits, opening up new venues to manipulate the states of qubits and photons in quantum information devices and quantum computers.A number of studies have constructed coarse-grained (CG) models of water to understand its anomalous properties. Most of these properties emerge at low temperatures, and an accurate CG model needs to be applicable to these low-temperature ranges. However, direct use of CG models parameterized from other temperatures, e.g., room temperature, encounters a problem known as transferability, as the CG potential essentially follows the form of the many-body CG free energy function. Therefore, temperature-dependent changes to CG interactions must be accounted for. The collective behavior of water at low temperature is generally a many-body process, which often motivates the use of expensive many-body terms in the CG interactions. To surmount the aforementioned problems, we apply the Bottom-Up Many-Body Projected Water (BUMPer) CG model constructed from Paper I to study the low-temperature behavior of water. We report for the first time that the embedded three-body interaction enables BUMPer, despite its pairwise form, to capture the growth of ice at the ice/water interface with corroborating many-body correlations during the crystal growth.