Unit vector

Figure 3 Snapshots of the shear wavefronts for different types of weld material to show the direction of the wave unit vector k (a phase velocity unit vector Cp ) and the group velocity unit vector...

Next, we denote the line between the centres of the two particles at the point of closest approach by the unit vector k. In figure A3.1.7 it can also be seen that the vectors -g and g are each other s mirror images in the direction of kin the plane of the trajectory of particles ... 

The primes and subscripts on the /s refer to their velocity arguments, and the primed velocities in the gain tenn should be regarded as fiinctions of the imprimed quantities according to (A3.1.36). It is often convenient to rewrite the integral over the impact parameter and the azimuthal angle as an integral over the unit vector kas... 

Thennotropic liquid crystal phases are fonned by rodlike or disclike molecules. However, in the following we consider orientational ordering of rodlike molecules for definiteness, although the same parameters can be used for discotics. In a liquid crystal phase, the anisotropic molecules tend to point along the same direction. This is known as the director, which is a unit vector denoted n. 

Figure C3.4.1. Example of the spatial orientation of tlrree major vectors / Aaird R, unit vectors of tire donor...

The procedure Split selects the internal displacement coordinates, q, and momenta, tt, (describing vibrations), the coordinates, r, and velocities, v, of the centers of molecular masses, angular velocities, a>, and directional unit vectors, e, of the molecules from the initial Cartesian coordinates, q, and from momenta, p. Thus, the staring values for algorithm loop are prepared. Step 1 Vibration... 

The procedure Merge transforms the internal displacement coordinates and momenta, the coordinates and velocities of centers of masses, and directional unit vectors of the molecules back to the Cartesian coordinates and momenta. Evolve with Hr = Hr(q) means only a shift of all momenta for a corresponding impulse of force (SISM requires only one force evaluation per integration step). 

The numbers xi are called the components of the vector x in the directions of some n elementary unit vectors ... 

The unit vectors Ci, whose exact definition, meaning and interpretation depend on the particular application at hand, are called basis vectors and form the elements of a basis. They are particularly simple to work with because they are orthogonal. This means that... 

Before considering other concepts and group-theoretical machinery, it should once again be stressed that these same tools can be used in symmetry analysis of the translational, vibrational and rotational motions of a molecule. The twelve motions of NH3 (three translations, three rotations, six vibrations) can be described in terms of combinations of displacements of each of the four atoms in each of three (x,y,z) directions. Hence, unit vectors placed on each atom directed in the x, y, and z directions form a basis for action by the operations S of the point group. In the case of NH3, the characters of the resultant 12x12 representation matrices form a reducible representation... 

You should try to prove this. For example under Gy, the H2 and H3 atoms are interchanged, so unit vectors on either one will not contribute to the trace. Unit z-vectors on N and H1 remain unchanged as well as the corresponding y-vectors. However, the x-... 

The easiest way to proceed is to use vectors to describe this part of the problem. We represent the distance between the pair of scattering sites by the vector OP the length of which is simply r. To express di and d2 in terms of OP we construct the unit vectors a and b which are parallel to the incident and scattered directions, respectively. The projection of OP into direction a, given by the dot product of these two vectors, equals dj. Likewise, the projection of OP into direction b gives d2. Therefore we can write... 

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