Commit JT 111519
- modified documentation spin (compute and exchange) - modified compute spin for Ts
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@ -1,11 +1,15 @@
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\documentclass[preview]{standalone}
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\documentclass[preview]{standalone}
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\usepackage{varwidth}
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\usepackage{varwidth}
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\usepackage[utf8x]{inputenc}
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\usepackage[utf8x]{inputenc}
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\usepackage{amsmath,amssymb,amsthm,bm}
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\usepackage{amsmath, amssymb, graphics, setspace}
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\begin{document}
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\begin{document}
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\begin{varwidth}{50in}
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\begin{varwidth}{50in}
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\begin{equation}
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\begin{equation}
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\bm{H}_{ex} ~=~ -\sum_{i,j,i\neq j}^{N} {J} \left(r_{ij} \right)\, \vec{s}_{i}\cdot \vec{s}_{j} \nonumber
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H_{ex} =
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-\sum_{i,j}^N J_{ij} (r_{ij}) \,\vec{s}_i \cdot \vec{s}_j
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%&{\rm ~if~}& \vec{m}_i^I \times \vec{m}_i^F
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, \nonumber
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\end{equation}
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\end{equation}
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\end{varwidth}
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\end{varwidth}
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\end{document}
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\end{document}
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@ -24,17 +24,15 @@ compute out_mag all spin :pre
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Define a computation that calculates magnetic quantities for a system
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Define a computation that calculates magnetic quantities for a system
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of atoms having spins.
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of atoms having spins.
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This compute calculates 6 magnetic quantities.
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This compute calculates the following 6 magnetic quantities:
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The three first quantities are the x,y and z coordinates of the total
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magnetization.
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The fourth quantity is the norm of the total magnetization.
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The fifth quantity is the magnetic energy.
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the three first quantities are the x,y and z coordinates of the total
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magnetization, :ulb,l
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the fourth quantity is the norm of the total magnetization, :l
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The fifth quantity is the magnetic energy (in eV), :l
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The sixth one is referred to as the spin temperature, according
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The sixth one is referred to as the spin temperature, according
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to the work of "(Nurdin)"_#Nurdin1.
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to the work of "(Nurdin)"_#Nurdin1. :l
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:ule
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The simplest way to output the results of the compute spin calculation
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The simplest way to output the results of the compute spin calculation
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is to define some of the quantities as variables, and to use the thermo and
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is to define some of the quantities as variables, and to use the thermo and
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@ -30,14 +30,15 @@ pairs of magnetic spins:
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:c,image(Eqs/pair_spin_exchange_interaction.jpg)
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:c,image(Eqs/pair_spin_exchange_interaction.jpg)
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where si and sj are two neighboring magnetic spins of two particles,
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where si and sj are two neighboring magnetic spins of two particles,
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rij = ri - rj is the inter-atomic distance between the two particles,
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rij = |ri - rj| is the inter-atomic distance between the two particles,
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and J(rij) is a function defining the intensity and the sign of the exchange
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and J(rij) is a function defining the intensity and the sign of the exchange
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interaction for different neighboring shells. This function is defined as:
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interaction for different neighboring shells. This function is defined as:
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:c,image(Eqs/pair_spin_exchange_function.jpg)
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:c,image(Eqs/pair_spin_exchange_function.jpg)
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where a, b and d are the three constant coefficients defined in the associated
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where a, b and d are the three constant coefficients defined in the associated
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"pair_coeff" command (see below for more explanations).
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"pair_coeff" command, and Rc is the radius cutoff associated to
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the pair interaction (see below for more explanations).
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The coefficients a, b, and d need to be fitted so that the function above matches with
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The coefficients a, b, and d need to be fitted so that the function above matches with
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the value of the exchange interaction for the N neighbor shells taken into account.
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the value of the exchange interaction for the N neighbor shells taken into account.
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@ -129,7 +129,8 @@ void ComputeSpin::compute_vector()
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magtot[2] *= scale;
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magtot[2] *= scale;
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magtot[3] = sqrt((magtot[0]*magtot[0])+(magtot[1]*magtot[1])+(magtot[2]*magtot[2]));
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magtot[3] = sqrt((magtot[0]*magtot[0])+(magtot[1]*magtot[1])+(magtot[2]*magtot[2]));
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spintemperature = hbar*tempnumtot;
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spintemperature = hbar*tempnumtot;
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spintemperature /= (kb*tempdenomtot);
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// spintemperature /= (kb*tempdenomtot);
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spintemperature /= (2.0*kb*tempdenomtot);
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vector[0] = magtot[0];
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vector[0] = magtot[0];
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vector[1] = magtot[1];
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vector[1] = magtot[1];
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