Effects of a static electric field on two-color photoassociation between different atoms

We study non-perturbative effects of a static electric field on two-color photoassociation of different atoms. A static electric field induces anisotropy in scattering between two different atoms and hybridizes field-free rotational states of heteronuclear dimers or polar molecules. In a previous paper [D. Chakraborty $\it {et.}$ $\it {al.}$, J. Phys. B 44, 095201 (2011)], the effects of a static electric field on one-color photoassociation between different atoms has been described through field-modified ground-state scattering states, neglecting electric field effects on heteronuclear diatomic bound states. To study the effects of a static electric field on heteronuclear bound states, and the resulting influence on Raman-type two-color photoassociation between different atoms in the presence of a static electric field, we develop a non-perturbative numerical method to calculate static electric field-dressed heteronuclear bound states. We show that the static electric field induced scattering anisotropy as well as hybridization of rotational states strongly influence two-color photoassociation spectra, leading to significant enhancement in PA rate and large shift. In particular, for static electric field strengths of a few hundred kV/cm, two-color PA rate involving high-lying bound states in electronic ground-state increases by several orders of magnitude even in the weak photoassociative coupling regime

A Theoretical Development of Distance Measure for Intuitionistic Fuzzy Numbers

The objective of this paper is to introduce a distance measure for intuitionistic fuzzy numbers. Firstly the existing distance measures for intuitionistic fuzzy sets are analyzed and compared with the help of some examples. Then the new distance measure for intuitionistic fuzzy numbers is proposed based on interval difference. Also in particular the type of distance measure for triangle intuitionistic fuzzy numbers is described. The metric properties of the proposed measure are also studied. Some numerical examples are considered for applying the proposed measure and finally the result is compared with the existing ones

Resonant enhancement of ultracold photoassociation rate by electric field induced anisotropic interaction

We study the effects of a static electric field on the photoassociation of a heteronuclear atom-pair into a polar molecule. The interaction of permanent dipole moment with a static electric field largely affects the ground state continuum wave function of the atom-pair at short separations where photoassociation transitions occur according to Franck-Condon principle. Electric field induced anisotropic interaction between two heteronuclear ground state atoms leads to scattering resonances at some specific electric fields. Near such resonances the amplitude of scattering wave function at short separation increases by several orders of magnitude. As a result, photoaasociation rate is enhanced by several orders of magnitude near the resonances. We discuss in detail electric field modified atom-atom scattering properties and resonances. We calculate photoassociation rate that shows giant enhancement due to electric field tunable anisotropic resonances. We present selected results among which particularly important are the excitations of higher rotational levels in ultracold photoassociation due to electric field tunable resonances.Comment: 14 pages,9 figure

Interstitial Voids and Resultant Density of Liquid Water: A First-Principles Molecular Dynamics Study

Many anomalous properties of water can be explained on the basis of the coexistence of more than one density states: high-density water (HDW) and low-density water (LDW). We investigated these two phases of water molecules through first-principles molecular dynamics simulations using density functional theory (DFT) in conjunction with various van der Waals-corrected exchange and correlation functionals. Different density regions were found to exist due to the difference in short-range and long-range forces present in DFT potentials. These density regions were identified and analyzed on the basis of the distribution of molecules and voids present. We defined a local structure index to distinguish and find the probability of occurrence of these different states. HDW and LDW arise due to the presence of “interstitial water” molecules in between the first and second coordination shells. The population of interstitial water molecules is found to affect the overall dynamics of the system as they change the hydrogen bond pattern

Pressure effects on diffusion in liquid ammonia: a simulation study using a combination of isobaric-isothermal and microcanonical molecular dynamics

The effects of pressure on translational and rotational diffusion in liquid ammonia are investigated by means of molecular dynamics simulations. Calculations are done at two different temperatures and at many different pressures by using a two-part protocol involving molecular dynamics in isobaric-isothermal ensemble in the first part and in microcanonical ensemble in the second part. Our results are analyzed in terms of pressure-induced changes in structural properties such as packing and hydrogen bond properties. Also, the present results of liquid ammonia are compared with corresponding results for other hydrogen bonded liquids that were reported in recent years

Effect of Water Models on The Stability of RNA: Role of Counter-Ions

Various force fields and water model potentials influence significantly RNA conformations. The polyanionic nature of RNA attracts the water molecules and the counter ions which in turn affects their stability. The interfacial water's structural and dynamic aspects affect the RNA's base-pair opening and denaturation by breaking or making inter/intra-hydrogen bonds. Herein, we employed an MD simulations study using SPC/E and modified TIP3P water models in combination with different force fields CHARMM and AMBER to find their influence on the hydration shell of the SARS-CoV-2 RNA genome at different temperatures. AMBER-mTIP3P model was found to give more dynamic and transient conformations for RNA. The lower dielectric constant of the SPC/E model helps in the formation of the ion-contact pair near the negatively charged phosphate group (Na+-PO4−) leading to strong RNA-ion interaction and strong hydration shells having higher hydrogen bond lifetime. The Na+ ion survival probability at the interface was found to be more in the SPC/E model. At lower temperatures, the water molecules inside these hydration shells were found to be inhomogeneous, with lower void space, higher-coordinated, and non-tetrahedral. The higher dielectric constant of the mTIP3P model screened out the attraction between the ion pairs leading to a more homogenous solvation shell having a lesser hydrogen bond lifetime and more diffusive water. The distribution of the ions near the RNA structure is confirmed by metadynamics simulations. Both water models were found to disrupt the base pair orientation due to the formation of water bridges between the O2ʹ group of RNA and the water molecules

Analysis of Free and Bound NADPH in Aqueous Extract of Human placenta Used as Wound Healer.

NADPH is an important biomolecule involved in cellular regeneration. The distribution of free and bound NADPH in aqueous extract of human placenta used as a potent wound healer has been analyzed. Quantification from fluorescence and immuno-affinity chromatography indicates that 75.1±2.2% of NADPH present in the extract exists as free nucleotide or bound to very small peptides or amino acids whereas the rest remains bound to large peptides. Inability to dissociate the bound form of the nucleotide from the large peptides using urea or guanidium hydrochloride indicates that the binding is covalent. Identification of a fragmented mass of m/z 382.94 (nicotinamide + sugar + phosphate) from the NADPH-peptide conjugates supported the intactness of the nicotinamide moiety. Glutathione reductase assay indicated that 95.2±3.5% of the total NADPH pool of the extract can act as cosubstrate of the enzyme. This indicates that while a major fraction of free NADPH of the extract is easily available for cellular processes, the rest can also function locally where the conjugated peptides are deposited