Surface Normal Orientation Research Articles

In situ X-ray diffraction evidence of field-induced transitions in a PbHfO3 single crystal

Antiferroelectric (AFE) materials are interesting due to recent discoveries of new prospective applications, although the mechanisms of the phase transitions that are at the heart of these applications remain incompletely understood. This work is devoted to the study of a single crystal of a model AFE, lead hafnate, by X-ray diffraction with in situ application of an electric field to trigger the transition to a polar phase. Two consecutive experiments were carried out on a 35 µm thick plate with [110] surface normal orientation over a field range from 0 to 330 kV cm−1 and back. A sharp drop in the intensity of R- and Σ-type reflections around 225 kV cm−1 was registered, with almost complete disappearance after 250 kV cm−1. This is compatible with a field-induced phase transition from the AFE to the R3m polar phase, which was suggested earlier on the basis of non-diffraction characterizations. X-ray diffraction reveals that the AFE domains with displacements parallel to the field direction react much more smoothly to the field, gradually reducing the AFE order at very small fields instead of holding it almost constant up to the critical field value, which is naturally expected. This expectation is fulfilled for domains with other orientations, but only for the first switching cycle; in the second switching cycle the AFE order already shows a notable decrease at subcritical fields. It is suggested that these observations could be linked with the antiphase domain wall population being affected by the field, which is consistent with the observation of diffuse rods between the Γ and Σ points. Another remarkable observation is the much smoother recovery of the AFE phase compared with its sharp disappearance at the critical field.

Modeling of thin-film interference filters on structured substrates: microfacet-based BSDF versus ray tracing.

We compare two model approaches for the ray optical description of PV modules with coloring based on an interference layer system on the inside of the cover glass. The light scattering is described by a microfacet-based bidirectional scattering distribution function (BSDF) model on the one hand and ray tracing on the other hand. We show that the microfacet-based BSDF model is largely sufficient for the structures used in the context of the MorphoColor application. A structure inversion shows a significant influence only for extreme angles and very steep structures showing correlated heights and surface normal orientations. Regarding an angle-independent color appearance, the model-based comparison of possible module configurations shows a clear advantage of a structured layer system compared to planar interference layers in combination with a scattering structure on the front side of the glass.

TriSurfaceImmersion: Computing volume fractions and signed distances from triangulated surfaces immersed in unstructured meshes

We propose a numerical method that enables the calculation of volume fractions from triangulated surfaces immersed in unstructured meshes. First, the signed distances are calculated geometrically near the triangulated surface. For this purpose, the computational complexity has been reduced by using an octree space subdivision. Second, an approximate solution of the Laplace equation is used to propagate the inside/outside information from the surface into the solution domain. Finally, volume fractions are computed from the signed distances in the vicinity of the surface. The volume fraction calculation utilizes either geometrical intersections or a polynomial approximation based on signed distances. An adaptive tetrahedral decomposition of polyhedral cells ensures a high absolute accuracy. The proposed method extends the admissible shape of the fluid interface (surface) to triangulated surfaces that can be open or closed, disjoint, and model objects of technical geometrical complexity.Current results demonstrate the effectiveness of the proposed algorithm for two-phase flow simulations of wetting phenomena, but the algorithm has broad applicability. For example, the calculation of volume fractions is crucial for achieving numerically stable simulations of surface tension-driven two-phase flows with the unstructured Volume-of-Fluid method. The method is applicable as a discrete phase-indicator model for the unstructured hybrid Level Set/Front Tracking method.The implementation is available on GitLab [27]. Program summaryProgram Title: argo/triSurfaceImmersionCPC Library link to program files:https://doi.org/10.17632/7g72xrcgjp.1Developer's repository link:https://gitlab.com/leia-methods/argoLicensing provisions: GPLv3Programming language: C++Nature of problem: Computing volume fractions and signed distances from triangulated surfaces immersed in unstructured meshes.Solution method: First, the algorithm computes minimal signed distances between mesh points (cell centers and cell corner-points) and the triangulated surface, in the close vicinity of the surface. The sign is computed with respect to the surface normal orientation. Afterwards, the sign is propagated throughout the unstructured volume mesh by an approximate solution of a diffusion equation. The bulk cells' volume fractions are set, and interface cells are identified based on the signed distances. Volume fractions in cells intersected by the triangulated surface mesh are either computed by geometric intersections between surface triangles and a cell or by an approximation of the volume fraction approximation from signed distances, coupled with tetrahedral cell decomposition and refinement.Additional comments including restrictions and unusual features: The volume mesh can consist of cells of arbitrary shape. The surface mesh normal vectors need to be oriented consistently.

Elastic constants of cubic boron phosphide and boron arsenide

We report the room temperature elastic constants of boron phosphide (BP) and boron arsenide (BAs) single crystals derived from Brillouin frequencies measured by picosecond interferometry. The synthesis of BP and BAs with thermal conductivity as high as 540 and $1000\phantom{\rule{0.16em}{0ex}}\mathrm{W}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{\text{--}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\text{--}1}$, respectively, has made them promising materials for thermal management. Accurate measurements of elastic constants are needed to assess the accuracy of computational modeling of the lattice dynamics. The crystals are cut and polished in different orientations to access waves traveling along different directions. The surface normal orientations of the crystals are determined using electron backscattering diffraction. We studied the Brillouin frequencies of quasilongitudinal waves in five different orientations of BP and BAs crystals. Quasishear waves were observed in two orientations of BP and one orientation of BAs. The propagation directions and acoustic velocities are used to construct Christoffel equations which are then solved for the elastic constants. We report ${C}_{11}$, ${C}_{12}$, and ${C}_{44}$ values of 354 \ifmmode\pm\else\textpm\fi{} 5 GPa, 83 \ifmmode\pm\else\textpm\fi{} 15 GPa, and 190 \ifmmode\pm\else\textpm\fi{} 8 GPa for BP and 291 \ifmmode\pm\else\textpm\fi{} 5 GPa, 76 \ifmmode\pm\else\textpm\fi{} 13 GPa, and 173 \ifmmode\pm\else\textpm\fi{} 6 GPa for BAs. The measured elastic constants for BAs differ by less than 5% and 17% from calculated elastic constants obtained through local density approximation and Perdew-Burke-Ernzerhof density functional calculations, respectively. In most cases, the measured elastic constants are larger than the calculated elastic constants.

Growth mechanism and domain structure study on epitaxial BiFeO3 film grown on (La0.3Sr0.7)(Al0.65Ta0.35)O3

A BiFeO3 (BFO) film is epitaxially grown on an (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) substrate to investigate the lattice mismatch effect on the domain structure and lattice strain status within the BFO film. Atomic resolution scanning transmission electron microscope image, selected area electron diffraction (SAED) patterns, and X-ray reciprocal space mapping (XRSM) data clearly reveal that the lattice strain originating from the lattice mismatch between BFO and LSAT is relaxed by causing misfit dislocations in the BFO film. The SAED and XRSM data indicate that the crystal structure of BFO film is rhombohedral with the space group R3c. In particular, XRSM data acquired along two different in-plane orientations reveal that the BFO layer consists of two different domains that were 90° off each other with respect to the surface normal orientation. An atomistic model based on the crystal orientation relation found by SAED and XRSM shows that (1) the ferroelectric polarization axes of both domains are 35.6° with respect to the BFO film surface and (2) the two domains are consistent with the so-called 71° (and/or 109°) ferroelectric domains reported previously. The lattice mismatch of ∼2.8% calculated based on the epitaxial relation is proposed to be too large to be stored as elastic strain energy within the BFO layer.

Anisotropy effects on gaseous nitriding of austenitic stainless steel single crystals

Low temperature nitrided austenitic stainless steel exhibits strong orientation dependent case growth kinetics. Anisotropy effects during low temperature gaseous nitriding of single crystals of austenitic stainless steel with surface-normal orientations 〈100〉, 〈111〉 and 〈10 7 2〉 were investigated with thermogravimetry, X-ray diffractometry (XRD), glow discharge optical emission spectroscopy (GD-OES), nano-indentation and electron back-scatter diffraction (EBSD). Case growth kinetics were fastest for 〈100〉 and slowest for 〈111〉. Depth-profiling over the case depth was accomplished by successive layer removal combined with X-ray diffraction and nano-indentation. The results indicate that anisotropic case-growth kinetics is related to early nucleation of long-range ordered (LRO) over-stoichiometric γ’N−Me4N1+x (Me=metal atoms) in 〈100〉, which is inseparable from short range ordered (SRO) expanded austenite, γN. Depth ranges of elasto-plastic and purely plastic accommodation of the nitrogen induced lattice expansion were distinguished. In the elasto-plastic region stress-gradient enhanced diffusion of N is observed.

Depth-based human activity recognition via multi-level fused features and fast broad learning system

Human activity recognition using depth videos remains a challenging problem while in some applications the available training samples is limited. In this article, we propose a new method for human activity recognition by crafting an integrated descriptor called multi-level fused features for depth sequences and devising a fast broad learning system based on matrix decomposition for classification. First, the surface normals are computed from original depth maps; the histogram of the surface normal orientations is obtained as a low-level feature by accumulating the contributions from normals, then a high-level feature is acquired by sparse coding and pooling on the aggregation of polynormals. After that, the principal component analysis is applied to the conjunction of the two-level features in order to obtain a low-dimensional and discriminative fused feature. At last, fast broad learning system based on matrix decomposition is proposed to accelerate the training process and enhance the classification results. The recognition results on three benchmark data sets show that our method outperforms the state-of-the-art methods in term of accuracy, especially when the number of training samples is small.

Large-area surface topography analysis of additively manufactured metallic materials using directional reflectance microscopy

The surface topography of additively manufactured metals carries valuable information about the mechanisms involved during materials formation. As such, it may be used as an indirect measure of materials quality, both during and after production. Standard surface analysis techniques, however, are characterized by narrow field of view and low data acquisition rate, making them unsuited to rapidly characterize large areas. In this work, we describe a novel method to quantify the three-dimensional surface topography of a 1 cm3 metal sample produced by selective laser melting. The method relies on directional reflectance microscopy—an optical technique that quantifies surface reflectance as a function of the illumination angle. By fitting the directional reflectance measurements with a reflection model, we map the surface normal orientation and microscopic surface roughness over the entire sample surface at a spatial resolution of ~5.3μm. We also discuss the possibility of integrating our method within the additive process by reducing the number of measurements required to reconstruct surface topography. Because of the inexpensive equipment employed, the large field of view measurements, and rapid data acquisition speed, we believe that our method is a competitive alternative for analysing the surface topography—and thus the quality—of additively manufactured metals both during and after production.

A new 3D descriptor for human classification: application for human detection in a multi-kinect system

In this paper we present a new 3D descriptor for human classification and a human detection method based on this descriptor. The proposed 3D descriptor allows classification of an object represented by a point cloud, as human or non-human. It is derived from the well-known Histogram of Oriented Gradient by employing surface normals instead of gradients. The process consists in an appropriate subdivision of the object point cloud into blocks. These blocks provide the spatial distribution modeling of the surface normal orientation into the different parts of the object. This distribution modelling is expressed as a histogram. In addition we have set up a multi-kinect acquisition system that provides us with Complete Point Clouds (CPC) (i.e. 360° view). Such CPCs enable a suitable processing, particularly in case of occlusions. Moreover they allow for the determination of the human frontal orientation. Based on the proposed 3D descriptor, we have developed a human detection method that is applied on CPCs. First, we evaluated the 3D descriptor over a set of CPC candidates by using the Support Vector Machine (SVM) classifier. The learning process was conducted with the original CPC database that we have built. The results are very promising. The descriptor can discriminate human from non-human candidates and provides the frontal direction of humans with high precision. In addition we demonstrated that using the CPCs improves significantly the classification results in comparison with Single Point Clouds (i.e. points clouds acquired with only one kinect). Second, we compared our detection method with two others, namely the HOG detector on RGB images and a 3D HOG-based detection method that is applied on RGB-depth data. The obtained results on different situations show that the proposed human detection method provides excellent performances that outperform the other two detection methods.

Articular-surface-based automatic anatomical coordinate systems for the knee bones

Increasing use of patient-specific surgical procedures in orthopaedics means that patient-specific anatomical coordinate systems (ACSs) need to be determined. For knee bones, automatic algorithms constructing ACSs exist and are assumed to be more reliable than manual methods, although both approaches are based on non-unique numerical reconstructions of true bone geometries. Furthermore, determining the best algorithms is difficult, as algorithms are evaluated on different datasets. Thus, in this study, we developed 3 algorithms, each with 3 variants, and compared them with 5 from the literature on a dataset comprising 24 lower-limb CT-scans. To evaluate algorithms’ sensitivity to the operator-dependent reconstruction procedure, the tibia, patella and femur of each CT-scan were each reconstructed once by three different operators.Our algorithms use principal inertia axis (PIA), cross-sectional area, surface normal orientations and curvature data to identify the bone region underneath articular surfaces (ASs). Then geometric primitives are fitted to ASs, and the ACSs are constructed from the geometric primitive points and/or axes. For each bone type, the algorithm displaying the least inter-operator variability is identified. The best femur algorithm fits a cylinder to posterior condyle ASs and a sphere to the femoral head, average axis deviations: 0.12°, position differences: 0.20 mm. The best patella algorithm identifies the AS PIAs, average axis deviations: 0.91°, position differences: 0.19 mm. The best tibia algorithm finds the ankle AS center and the 1st PIA of a layer around a plane fitted to condyle ASs, average axis deviations: 0.38°, position differences: 0.27 mm.

Computer extracted shape features of prostate capsule from MRI to predict biochemical recurrence of prostate cancer post-treatment.

e16579 Background: Pre-treatment identification of biochemical recurrence (BCR) from MRI may enable the use of aggressive neo-adjuvant therapies for prostate cancer patients to improve prognosis. BCR is often associated with aggressive cancer growth and/or extra prostatic extension resulting in an irregular bulge and focal capsular retraction. This may induce differences in the shape of the prostate capsule between BCR positive (BCR+) and BCR negative (BCR-) patients as observed on MRI. In this work, we show that computer extracted shape features of the prostate capsule on MRI can identify patients that are at a risk of BCR post-treatment Methods: In a single centre IRB approved study, from a registry of 874 patients, availability of complete image datasets (T1w, T2w and ADC map); no treatment for PCa before MRI; presence of clinically localised PCa; availability of Gleason score; and data available for post-treatment PSA and follow-up for at least 3 years in patients without BCR were used as inclusion criteria to select 80 patients. The prostate capsule was manually segmented on T2w MRI by an experienced radiologist. Two atlases A+ and A- were created for BCR+ and BCR- patients respectively with similar Gleason score (6 to 9), similar numbers in each cohort (25 each) and similar tumor stage (T2 to T3). A t-test based analysis corrected for multiple comparison revealed statistically significant prostate shape differences between A+ and A- in surface of interest (SOI). Curvature features (magnitude and surface normal orientations) were extracted from SOI of the two cohorts. A random forest classifier was trained using the 50 training images (from A+ and A-) and validated using a hold-out validation set of 30 patients. Results: The inter-quartile range, variance, skewness and kurtosis of curvature magnitude and normal orientations were found to be predictive of BCR. The RF classifier trained using these features could predict BCR with an accuracy of 78% and an AUC of 0.71 in the validation set. Conclusions: Curvature magnitude and orientation features of the prostate capsule from the SOI may be predictive of BCR. In future a multi centre independent datasets will be used to validate the findings.

Nanoindentation study of the combined effects of crystallography, heat treatment and exposure to high-flux deuterium plasma in tungsten

tungsten samples were heat-treated to achieve partial recrystallization and exposed to high ion flux deuterium plasma at different temperatures and fluences. Continuous stiffness nanoindentation measurements of near-surface hardness were performed in the grains of specific annealing states and of specific crystallographic orientation, determined by electron backscatter diffraction (EBSD); indentation pile-up was investigated using surface profilometry. Bulk hardness of unexposed tungsten does not strongly depend on grain orientation, but depends on the annealing state of the grain, with values between ∼4.3 GPa for recrystallized grains and ∼5.5 for non-recrystallized ones. Grains with <111> surface normal orientation feature the least pile-up, while grains with <001> orientation the most; pile-up also depends on the annealing state, being generally lower in recrystallized grains. Plasma exposure leads to the increase of hardness, most significantly near the surface. The width of plasma-affected zone increases with the increase of exposure temperature and fluence, as well in recrystallized grains, correlating with the increase of diffusion depth. Plasma exposure does not lead to the emergence of orientation-dependence of hardness. Both indentation pile-up and near-surface indentation pop-ins are generally suppressed by plasma exposure.

Determination of sample surface topography using electron back-scatter diffraction patterns

The background of an electron backscattered diffraction pattern contains quantitative surface topography data. We propose a new approach to extract this topography from the location of the maximum background intensity in each diffraction pattern. Using specular reflection as a zero-th order approximation, we employ Monte Carlo simulations to determine corrections to the scattering angles, which then allow us to accurately determine the local surface normal. We derive the theoretical model and illustrate the approach experimentally using a β-Sn sphere, for which we determine the local surface normal orientation from the background intensity shifts in electron backscatter diffraction patterns.

Accurate 3D comparison of complex topography with terrestrial laser scanner: Application to the Rangitikei canyon (N-Z)

Surveying techniques such as terrestrial laser scanner have recently been used to measure surface changes via 3D point cloud (PC) comparison. Two types of approaches have been pursued: 3D tracking of homologous parts of the surface to compute a displacement field, and distance calculation between two point clouds when homologous parts cannot be defined. This study deals with the second approach, typical of natural surfaces altered by erosion, sedimentation or vegetation between surveys. Current comparison methods are based on a closest point distance or require at least one of the PC to be meshed with severe limitations when surfaces present roughness elements at all scales. To solve these issues, we introduce a new algorithm performing a direct comparison of point clouds in 3D. The method has two steps: (1) surface normal estimation and orientation in 3D at a scale consistent with the local surface roughness; (2) measurement of the mean surface change along the normal direction with explicit calculation of a local confidence interval. Comparison with existing methods demonstrates the higher accuracy of our approach, as well as an easier workflow due to the absence of surface meshing or Digital Elevation Model (DEM) generation. Application of the method in a rapidly eroding, meandering bedrock river (Rangitikei River canyon) illustrates its ability to handle 3D differences in complex situations (flat and vertical surfaces on the same scene), to reduce uncertainty related to point cloud roughness by local averaging and to generate 3D maps of uncertainty levels. We also demonstrate that for high precision survey scanners, the total error budget on change detection is dominated by the point clouds registration error and the surface roughness. Combined with mm-range local georeferencing of the point clouds, levels of detection down to 6mm (defined at 95% confidence) can be routinely attained in situ over ranges of 50m. We provide evidence for the self-affine behaviour of different surfaces. We show how this impacts the calculation of normal vectors and demonstrate the scaling behaviour of the level of change detection. The algorithm has been implemented in a freely available open source software package. It operates in complex 3D cases and can also be used as a simpler and more robust alternative to DEM differencing for the 2D cases.

Structural evolution of nanoporous gold during thermal coarsening

The three-dimensional evolution of nanoligaments of nanoporous gold created by Ag–Au dealloying was studied during isothermal coarsening by X-ray nanotomography and microbeam Laue diffraction. The surface normal orientation, curvature and size of the gold nanoligaments were measured as a function of coarsening time (from 2 to 320min). The following observations were made at 550, 600 and 650°C. First, the distribution of orientations for the surfaces of the nanoligaments becomes more anisotropic with coarsening time, with an increasing area of the surfaces having a low surface energy, consistent with the growth of facets. Second, the curvature distribution of the nanoligaments (scaled by their size) also evolves during coarsening. The evolution of both surface orientation and scaled surface curvature indicates that coarsening does not occur in a self-similar manner, i.e. the interfacial shape distribution of the gold nanoligaments is not self-similar over time as they coarsen. This is consistent with the ligament size not being described by a classical temporal power law for coarsening systems. All three effects, and in particular the increased prevalence of surfaces with a low surface energy at long coarsening times, may affect the surface functionalities and properties of nanoporous gold in various applications, e.g. as catalysts, sensors and actuators.

Gradient Response Maps for Real-Time Detection of Textureless Objects

We present a method for real-time 3D object instance detection that does not require a time-consuming training stage, and can handle untextured objects. At its core, our approach is a novel image representation for template matching designed to be robust to small image transformations. This robustness is based on spread image gradient orientations and allows us to test only a small subset of all possible pixel locations when parsing the image, and to represent a 3D object with a limited set of templates. In addition, we demonstrate that if a dense depth sensor is available we can extend our approach for an even better performance also taking 3D surface normal orientations into account. We show how to take advantage of the architecture of modern computers to build an efficient but very discriminant representation of the input images that can be used to consider thousands of templates in real time. We demonstrate in many experiments on real data that our method is much faster and more robust with respect to background clutter than current state-of-the-art methods.

Oriented Growth of Location-Controlled Si Crystal Grains by Ni Nano-Imprint and Excimer Laser Annealing

A new method of controlling the location and orientation of Si crystal grains by combining metal (Ni) nano-imprint and excimer laser annealing (ELA) using a double-layered Si thin-film structure was successfully demonstrated. Ni nano-imprint at the surface of the first amorphous Si (a-Si) film (25 nm thick) was performed to create {111}-oriented Si-crystal nuclei that act as the seed for the subsequent crystallization using ELA. The annealing that induces the formation of nuclei at the imprinted sites was carried out at temperatures below 450 °C to meet the requirement of low-temperature process. After the removal of Ni or Ni–silicide, the second a-Si film (75 nm thick) was deposited. XeCl-laser-based ELA of the sample resulted in the formation of approximately 2 µm sized Si crystal grains at controlled positions. Electron backscattering pattern (EBSP) analysis showed that the surface-normal orientation of all the location-controlled grains distributed less than 10° from <111 > crystal axis.

Control of grain boundary microstructures in molybdenum polycrystals by thermomechanical processing of single crystals

The formation of grain structures and grain boundary microstructures in polycrystalline molybdenum, produced by thermomechanical processing from cylindrical single crystals with different initial surface normal orientations of ⟨110⟩, ⟨111⟩ and ⟨112⟩, were investigated with the objective of controlling grain boundary microstructures. The polycrystalline specimens displayed different microstructures depending on the initial orientation of the single crystal and the deformed microstructure. The recrystallized microstructure was composed of some oriented-grain clusters, in which grains possessing a similar orientation were assembled. The frequency of low-angle boundaries was very high in the oriented-grain clusters. A close relationship also existed between the grain boundary character distribution (GBCD) and the triple junction distribution. Grain boundary microstructures were compared of bcc molybdenum and fcc polycrystalline materials with reference to path-dependent percolation resistance.

Preferred Orientation of Inconel 690 after Vibration Arc Oscillation Welding

To evaluate the crystal growth characteristics of vibration welding, Inconel 690 alloy was welded when subjected to synchronous mechanical vibrations. This study employs arc oscillation welding along with vibrations to obtain structures with the preferred orientation. The results show that the surface normal orientation of grains in vibrationless weld was {420} preferentially, but they were {200}, {311} and {420} preferentially in vibration welding. The microstructure between the first and the second pass weldings illustrates that vibrations disconnect the dendrite growth from the first pass weld to the second. The most recent grains were formed without relating to the neighbouring grain. In the vibrationless weld, the grain orientation was either parallel or perpendicular to the orientation of the nearby grains. Hence, the grains subjected to vibration welding have three orientations, but only one when subjected to vibrationless welding. On the other hand, secondary dendrite arms were rarely observed during vibration welding, but dendrites with orientations parallel to the vibration could grow easily and strongly. This result illustrates that vertical vibration encourages vertical dendrite growth and restricts their horizontal growth. [doi:10.2320/matertrans.MEP2007305]

Molecular models of a hydrated calcite mineral surface

Hydrated mineral surfaces play an important role in many processes in biological, geological, and industrial applications. An energy force field was developed for molecular mechanics and molecular dynamics simulations of hydrated carbonate minerals and was applied to investigate the behavior of water on the ( 10 1 ¯ 4 ) calcite surface. The force field is a significant development for large-scale molecular simulations of these systems, and provides good agreement with experimental and previous modeling results. Simulations indicate that water molecules are significantly ordered near the calcite surface. The predominant surface configuration (75–80%) results from coordination of a water molecule with a single calcium cation–carbonate anion pair, while the less common situation involves water coordination with two ion pairs. Surface restructuring and variation in coordination in the water layers results in distinct distances for water oxygens above the calcite surface—a two-component first monolayer (2.3 and 3.0 Å) and a secondary monolayer (5.0 Å). The different coordinations also alter lateral displacement, hydrogen bonding, and surface-normal orientation of the water molecules. The ordering of water molecules and the formation of a unique hydrogen bonding network at the calcite surface influence the physical properties of the interfacial water. Surface exchange of water molecules is observed by molecular dynamics simulation to occur at a rate of one exchange per 10 ps. Diffusion coefficients derived from mean square displacement analysis of atomic trajectories indicate a dependence of water transport based on the distance of the water molecules from the calcite surface.