consistently apply \vec{} macro to only the first text/character and not subscripts
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@ -28,15 +28,15 @@ The *dipole* angle style is used to control the orientation of a dipolar
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atom within a molecule :ref:`(Orsi) <Orsi>`. Specifically, the *dipole* angle
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style restrains the orientation of a point dipole :math:`\mu_j` (embedded in atom
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:math:`j`) with respect to a reference (bond) vector
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:math:`\vec{r_{ij}} = \vec{r_i} - \vec{r_j}`, where :math:`i` is another atom of
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:math:`\vec{r}_{ij} = \vec{r}_i - \vec{r}_j`, where :math:`i` is another atom of
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the same molecule (typically, :math:`i` and :math:`j` are also covalently bonded).
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It is convenient to define an angle gamma between the 'free' vector :math:`\vec{\mu_j}`
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and the reference (bond) vector :math:`\vec{r_{ij}}`:
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It is convenient to define an angle gamma between the 'free' vector :math:`\vec{\mu}_j`
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and the reference (bond) vector :math:`\vec{r}_{ij}`:
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.. math::
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\cos\gamma = \frac{\vec{\mu_j}\cdot\vec{r_{ij}}}{\mu_j\,r_{ij}}
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\cos\gamma = \frac{\vec{\mu}_j\cdot\vec{r}_{ij}}{\mu_j\,r_{ij}}
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The *dipole* angle style uses the potential:
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@ -53,23 +53,23 @@ potential using the 'chain rule' as in appendix C.3 of
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.. math::
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\vec{T_j} = \frac{2K(\cos\gamma - \cos\gamma_0)}{\mu_j\,r_{ij}}\, \vec{r_{ij}} \times \vec{\mu_j}
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\vec{T}_j = \frac{2K(\cos\gamma - \cos\gamma_0)}{\mu_j\,r_{ij}}\, \vec{r}_{ij} \times \vec{\mu}_j
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Example: if :math:`\gamma_0` is set to 0 degrees, the torque generated by
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the potential will tend to align the dipole along the reference
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direction defined by the (bond) vector :math:`\vec{r_{ij}}` (in other words, :math:`\vec{\mu_j}` is
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direction defined by the (bond) vector :math:`\vec{r}_{ij}` (in other words, :math:`\vec{\mu}_j` is
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restrained to point towards atom :math:`i`).
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The dipolar torque :math:`\vec{T_j}` must be counterbalanced in order to conserve
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The dipolar torque :math:`\vec{T}_j` must be counterbalanced in order to conserve
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the local angular momentum. This is achieved via an additional force
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couple generating a torque equivalent to the opposite of :math:`\vec{T_j}`:
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couple generating a torque equivalent to the opposite of :math:`\vec{T}_j`:
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.. math::
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-\vec{T_j} & = \vec{r_{ij}} \times \vec{F_i} \\
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\vec{F_j} & = -\vec{F_i}
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-\vec{T}_j & = \vec{r}_{ij} \times \vec{F}_i \\
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\vec{F}_j & = -\vec{F}_i
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where :math:`\vec{F_i}` and :math:`\vec{F_j}` are applied on atoms :math:`i`
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where :math:`\vec{F}_i` and :math:`\vec{F}_j` are applied on atoms :math:`i`
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and :math:`j`, respectively.
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The following coefficients must be defined for each angle type via the
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@ -66,8 +66,8 @@ The deviation is calculated as:
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\text{RMSD}(\mathbf{u}, \mathbf{v})
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= \min_{s, \mathbf{Q}} \sqrt{\frac{1}{N} \sum\limits_{i=1}^{N}
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{\left\lVert s[\vec{u_i} - \mathbf{\bar{u}}]
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- \mathbf{Q} \cdot \vec{v_i} \right\rVert}^2}
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{\left\lVert s[\vec{u}_i - \mathbf{\bar{u}}]
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- \mathbf{Q} \cdot \vec{v}_i \right\rVert}^2}
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Here, :math:`\vec u` and :math:`\vec v` contain the coordinates of the local
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and ideal structures respectively, :math:`s` is a scale factor, and
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@ -103,15 +103,15 @@ possible easy axis for the magnetic spins in the defined group:
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H_{cubic} = -\sum_{{ i}=1}^{N} K_{1}
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\Big[
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\left(\vec{s}_{i} \cdot \vec{n_1} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n_2} \right)^2 +
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\left(\vec{s}_{i} \cdot \vec{n_2} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n_3} \right)^2 +
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\left(\vec{s}_{i} \cdot \vec{n_1} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n_3} \right)^2 \Big]
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+K_{2}^{(c)} \left(\vec{s}_{i} \cdot \vec{n_1} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n_2} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n_3} \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_1 \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_2 \right)^2 +
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\left(\vec{s}_{i} \cdot \vec{n}_2 \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_3 \right)^2 +
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\left(\vec{s}_{i} \cdot \vec{n}_1 \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_3 \right)^2 \Big]
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+K_{2}^{(c)} \left(\vec{s}_{i} \cdot \vec{n}_1 \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_2 \right)^2
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\left(\vec{s}_{i} \cdot \vec{n}_3 \right)^2
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with :math:`K_1` and :math:`K_{2c}` (in eV) the intensity coefficients
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and :math:`\vec{n}_1`, :math:`\vec{n}_2` and :math:`\vec{n}_3`
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@ -96,29 +96,29 @@ force (F), and torque (T) between particles I and J.
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\left(\frac{\sigma}{r}\right)^6 \right] \\
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E_{qq} = & \frac{q_i q_j}{r} \\
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E_{qp} = & \frac{q}{r^3} (p \bullet \vec{r}) \\
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E_{pp} = & \frac{1}{r^3} (\vec{p_i} \bullet \vec{p_j}) -
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\frac{3}{r^5} (\vec{p_i} \bullet \vec{r}) (\vec{p_j} \bullet \vec{r}) \\
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E_{pp} = & \frac{1}{r^3} (\vec{p}_i \bullet \vec{p}_j) -
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\frac{3}{r^5} (\vec{p}_i \bullet \vec{r}) (\vec{p}_j \bullet \vec{r}) \\
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& \\
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F_{qq} = & \frac{q_i q_j}{r^3} \vec{r} \\
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F_{qp} = & -\frac{q}{r^3} \vec{p} + \frac{3q}{r^5}
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(\vec{p} \bullet \vec{r}) \vec{r} \\
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F_{pp} = & \frac{3}{r^5} (\vec{p_i} \bullet \vec{p_j}) \vec{r} -
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\frac{15}{r^7} (\vec{p_i} \bullet \vec{r})
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(\vec{p_j} \bullet \vec{r}) \vec{r} +
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\frac{3}{r^5} \left[ (\vec{p_j} \bullet \vec{r}) \vec{p_i} +
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(\vec{p_i} \bullet \vec{r}) \vec{p_j} \right] \\
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F_{pp} = & \frac{3}{r^5} (\vec{p}_i \bullet \vec{p}_j) \vec{r} -
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\frac{15}{r^7} (\vec{p}_i \bullet \vec{r})
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(\vec{p}_j \bullet \vec{r}) \vec{r} +
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\frac{3}{r^5} \left[ (\vec{p}_j \bullet \vec{r}) \vec{p}_i +
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(\vec{p}_i \bullet \vec{r}) \vec{p}_j \right] \\
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& \\
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T_{pq} = T_{ij} = & \frac{q_j}{r^3} (\vec{p_i} \times \vec{r}) \\
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T_{qp} = T_{ji} = & - \frac{q_i}{r^3} (\vec{p_j} \times \vec{r}) \\
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T_{pp} = T_{ij} = & -\frac{1}{r^3} (\vec{p_i} \times \vec{p_j}) +
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\frac{3}{r^5} (\vec{p_j} \bullet \vec{r})
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(\vec{p_i} \times \vec{r}) \\
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T_{pp} = T_{ji} = & -\frac{1}{r^3} (\vec{p_j} \times \vec{p_i}) +
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\frac{3}{r^5} (\vec{p_i} \bullet \vec{r})
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(\vec{p_j} \times \vec{r})
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T_{pq} = T_{ij} = & \frac{q_j}{r^3} (\vec{p}_i \times \vec{r}) \\
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T_{qp} = T_{ji} = & - \frac{q_i}{r^3} (\vec{p}_j \times \vec{r}) \\
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T_{pp} = T_{ij} = & -\frac{1}{r^3} (\vec{p}_i \times \vec{p}_j) +
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\frac{3}{r^5} (\vec{p}_j \bullet \vec{r})
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(\vec{p}_i \times \vec{r}) \\
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T_{pp} = T_{ji} = & -\frac{1}{r^3} (\vec{p}_j \times \vec{p}_i) +
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\frac{3}{r^5} (\vec{p}_i \bullet \vec{r})
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(\vec{p}_j \times \vec{r})
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where :math:`q_i` and :math:`q_j` are the charges on the two
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particles, :math:`\vec{p_i}` and :math:`\vec{p_j}` are the dipole
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particles, :math:`\vec{p}_i` and :math:`\vec{p}_j` are the dipole
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moment vectors of the two particles, r is their separation distance,
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and the vector r = Ri - Rj is the separation vector between the two
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particles. Note that Eqq and Fqq are simply Coulombic energy and
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@ -163,8 +163,8 @@ energy (E), force (F), and torque (T) between particles I and J:
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2\left(\frac{r}{r_c}\right)^{\!3}\right] (\vec{p}\bullet\vec{r}) \\
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E_{pp} = & \left[1-4\left(\frac{r}{r_c}\right)^{\!3} +
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3\left(\frac{r}{r_c}\right)^{\!4}\right]\left[\frac{1}{r^3}
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(\vec{p_i} \bullet \vec{p_j}) - \frac{3}{r^5}
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(\vec{p_i} \bullet \vec{r}) (\vec{p_j} \bullet \vec{r})\right] \\
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(\vec{p}_i \bullet \vec{p}_j) - \frac{3}{r^5}
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(\vec{p}_i \bullet \vec{r}) (\vec{p}_j \bullet \vec{r})\right] \\
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& \\
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F_{LJ} = & \left\{\left[48\epsilon \left(\frac{\sigma}{r}\right)^{\!12} -
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@ -182,37 +182,37 @@ energy (E), force (F), and torque (T) between particles I and J:
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\frac{q}{r^3}\left[1-3\left(\frac{r}{r_c}\right)^{\!2} +
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2\left(\frac{r}{r_c}\right)^{\!3}\right] \vec{p} \\
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F_{pp} = &\frac{3}{r^5}\Bigg\{\left[1-\left(\frac{r}{r_c}\right)^{\!4}\right]
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\left[(\vec{p_i}\bullet\vec{p_j}) - \frac{3}{r^2} (\vec{p_i}\bullet\vec{r})
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(\vec{p_j} \bullet \vec{r})\right] \vec{r} + \\
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\left[(\vec{p}_i\bullet\vec{p}_j) - \frac{3}{r^2} (\vec{p}_i\bullet\vec{r})
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(\vec{p}_j \bullet \vec{r})\right] \vec{r} + \\
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& \left[1 -
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4\left(\frac{r}{r_c}\right)^{\!3}+3\left(\frac{r}{r_c}\right)^{\!4}\right]
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\left[ (\vec{p_j} \bullet \vec{r}) \vec{p_i} + (\vec{p_i} \bullet \vec{r})
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\vec{p_j} -\frac{2}{r^2} (\vec{p_i} \bullet \vec{r})
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(\vec{p_j} \bullet \vec{r})\vec{r}\right] \Bigg\}
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\left[ (\vec{p}_j \bullet \vec{r}) \vec{p}_i + (\vec{p}_i \bullet \vec{r})
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\vec{p}_j -\frac{2}{r^2} (\vec{p}_i \bullet \vec{r})
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(\vec{p}_j \bullet \vec{r})\vec{r}\right] \Bigg\}
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.. math::
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T_{pq} = T_{ij} = & \frac{q_j}{r^3} \left[ 1 -
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3\left(\frac{r}{r_c}\right)^{\!2} +
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2\left(\frac{r}{r_c}\right)^{\!3}\right] (\vec{p_i}\times\vec{r}) \\
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2\left(\frac{r}{r_c}\right)^{\!3}\right] (\vec{p}_i\times\vec{r}) \\
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T_{qp} = T_{ji} = & - \frac{q_i}{r^3} \left[ 1 -
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3\left(\frac{r}{r_c}\right)^{\!2} +
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2\left(\frac{r}{r_c}\right)^{\!3} \right] (\vec{p_j}\times\vec{r}) \\
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2\left(\frac{r}{r_c}\right)^{\!3} \right] (\vec{p}_j\times\vec{r}) \\
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T_{pp} = T_{ij} = & -\frac{1}{r^3}\left[1-4\left(\frac{r}{r_c}\right)^{\!3} +
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e3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p_i} \times \vec{p_j}) + \\
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e3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p}_i \times \vec{p}_j) + \\
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& \frac{3}{r^5}\left[1-4\left(\frac{r}{r_c}\right)^{\!3} +
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3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p_j}\bullet\vec{r})
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(\vec{p_i} \times \vec{r}) \\
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3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p}_j\bullet\vec{r})
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(\vec{p}_i \times \vec{r}) \\
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T_{pp} = T_{ji} = & -\frac{1}{r^3}\left[1-4\left(\frac{r}{r_c}\right)^{\!3} +
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3\left(\frac{r}{r_c}\right)^{\!4}\right](\vec{p_j} \times \vec{p_i}) + \\
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3\left(\frac{r}{r_c}\right)^{\!4}\right](\vec{p}_j \times \vec{p}_i) + \\
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& \frac{3}{r^5}\left[1-4\left(\frac{r}{r_c}\right)^{\!3} +
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3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p_i} \bullet \vec{r})
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(\vec{p_j} \times \vec{r})
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3\left(\frac{r}{r_c}\right)^{\!4}\right] (\vec{p}_i \bullet \vec{r})
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(\vec{p}_j \times \vec{r})
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where :math:`\epsilon` and :math:`\sigma` are the standard LJ
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parameters, :math:`r_c` is the cutoff, :math:`q_i` and :math:`q_j` are
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the charges on the two particles, :math:`\vec{p_i}` and
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:math:`\vec{p_j}` are the dipole moment vectors of the two particles,
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the charges on the two particles, :math:`\vec{p}_i` and
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:math:`\vec{p}_j` are the dipole moment vectors of the two particles,
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r is their separation distance, and the vector r = Ri - Rj is the
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separation vector between the two particles. Note that Eqq and Fqq
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are simply Coulombic energy and force, Fij = -Fji as symmetric forces,
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@ -68,13 +68,13 @@ of 3 terms
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\vec{f} = & (F^C + F^D + F^R) \hat{r_{ij}} \qquad \qquad r < r_c \\
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F^C = & A w(r) \\
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F^D = & - \gamma w^2(r) (\hat{r_{ij}} \bullet \vec{v_{ij}}) \\
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F^D = & - \gamma w^2(r) (\hat{r_{ij}} \bullet \vec{v}_{ij}) \\
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F^R = & \sigma w(r) \alpha (\Delta t)^{-1/2} \\
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w(r) = & 1 - \frac{r}{r_c}
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where :math:`F^C` is a conservative force, :math:`F^D` is a dissipative
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force, and :math:`F^R` is a random force. :math:`\hat{r_{ij}}` is a
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unit vector in the direction :math:`r_i - r_j`, :math:`\vec{v_{ij}}` is
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unit vector in the direction :math:`r_i - r_j`, :math:`\vec{v}_{ij}` is
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the vector difference in velocities of the two atoms :math:`\vec{v}_i -
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\vec{v}_j`, :math:`\alpha` is a Gaussian random number with zero mean
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and unit variance, *dt* is the timestep size, and :math:`w(r)` is a
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@ -56,13 +56,13 @@ given as a sum of 3 terms
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\vec{f} = & (F^C + F^D + F^R) \hat{r_{ij}} \qquad \qquad r < r_c \\
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F^C = & A w(r) \\
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F^D = & - \gamma w^2(r) (\hat{r_{ij}} \bullet \vec{v_{ij}}) \\
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F^D = & - \gamma w^2(r) (\hat{r_{ij}} \bullet \vec{v}_{ij}) \\
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F^R = & \sigma w(r) \alpha (\Delta t)^{-1/2} \\
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w(r) = & 1 - \frac{r}{r_c}
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where :math:`F^C` is a conservative force, :math:`F^D` is a dissipative
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force, and :math:`F^R` is a random force. :math:`\hat{r_{ij}}` is a
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unit vector in the direction :math:`r_i - r_j`, :math:`\vec{v_{ij}}` is
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unit vector in the direction :math:`r_i - r_j`, :math:`\vec{v}_{ij}` is
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the vector difference in velocities of the two atoms, :math:`\vec{v}_i -
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\vec{v}_j`, :math:`\alpha` is a Gaussian random number with zero mean
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and unit variance, *dt* is the timestep size, and :math:`w(r)` is a
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@ -99,9 +99,9 @@ energies are computed within style *dpd/fdt/energy* as:
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.. math::
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du_{i}^{cond} = & \kappa_{ij}(\frac{1}{\theta_{i}}-\frac{1}{\theta_{j}})\omega_{ij}^{2} + \alpha_{ij}\omega_{ij}\zeta_{ij}^{q}(\Delta{t})^{-1/2} \\
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du_{i}^{mech} = & -\frac{1}{2}\gamma_{ij}\omega_{ij}^{2}(\frac{\vec{r_{ij}}}{r_{ij}}\bullet\vec{v_{ij}})^{2} -
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du_{i}^{mech} = & -\frac{1}{2}\gamma_{ij}\omega_{ij}^{2}(\frac{\vec{r}_{ij}}{r_{ij}}\bullet\vec{v}_{ij})^{2} -
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\frac{\sigma^{2}_{ij}}{4}(\frac{1}{m_{i}}+\frac{1}{m_{j}})\omega_{ij}^{2} -
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\frac{1}{2}\sigma_{ij}\omega_{ij}(\frac{\vec{r_{ij}}}{r_{ij}}\bullet\vec{v_{ij}})\zeta_{ij}(\Delta{t})^{-1/2}
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\frac{1}{2}\sigma_{ij}\omega_{ij}(\frac{\vec{r}_{ij}}{r_{ij}}\bullet\vec{v}_{ij})\zeta_{ij}(\Delta{t})^{-1/2}
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where
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