Structure: 29791 spins arranged on a three dimensional so-called SC lattice

• WU Name: SC_29791_cyc_*
• Number of Spins: 29791
• Number of Spins over all: 29791
• CPU-time: ca. 1:45 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

29791 spins arranged on a three dimensional so-called SC lattice. Here, SC means "simple cubic" with the property that each spin (yellow sphere) is interacting with its 6 nearest neighbors (red spheres). The figure on the right-hand side shows the SC unit cell in detail. The whole 3D structure is build of these little unit cells. To see the relation between the 3D structure and the unit cell just look at the grey sphere which is connected to the 3 next neighboring spins of that unit cell and to the 3 neighboring spins of 3 other unit cells adjacent to it.

With this calculation we want to test the efficiency of a new Monte Carlo routine and calculate the critical temperature of a large magnetic system. To do so we have to perform 250.000 Monte Carlo steps per temperature value ranging from 1 to 1000 Kelvin. Using Spinhenge@home we can distribute the whole calculation using more than 150.000 work units.

Structure: 9261 spins arranged on a three dimensional so-called BCC lattice

• WU Name: bcc_lattice_*
• Number of Spins: 9261
• Number of Spins over all: 9261
• CPU-time: ca. 1:00 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

9261 spins arranged on a three dimensional so-called BCC lattice. Here, BCC means "body centered cubic" with the property that each spin (yellow sphere) is interacting with its 8 nearest neighbors (red spheres).

With this calculation we want to test the efficiency new Monte Carlo routine and calculate the critical temperature of a large magnetic system. To do so we have to perform 1000000 Monte Carlo steps per temperature value ranging from 1 to 1000 Kelvin. Using "Spinhenge@home" we can distribute the whole calculation using more than 100000 work units.

Structure: 120 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of a great rhombicosidodecahedron

• WU Name: great_rhombi_T25_* / great_rhombi_T30_*
• Number of Spins: 120
• Number of Spins over all: 120
• CPU-time: ca. 1:00 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

With this calculation we want to find out the magnetic properties of an artificial magnetic molecule which is composed of 120 spins located on the vertices of a so-called great rhombicosidodecahedron. This structure is the largest of all Archimedean solids! The great rhombicosidodecahedron is composed of squares, hexagons, and decagons. Here, we study the antiferromagnetic version and want to find out its magnetic properties. We have to perform some very low temperature simulation in order to find unusual behavior like phase transitions. To do so we have to do 1.0000.000 Monte Carlo steps per field value to get the necessary accuracy! There are two series with different magnetic fields. Using Spinhenge@home we distribute the whole calculation using more than 30.000 work units. Which is equal to more than 90.000 results which were sent out. We send out two different series of this with a different magnetic field. One will be calculated by T=25 and the other by T=30.

120 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of a great rhombicosidodecahedron - The largest of all Archimedean solids!

Structure: 60 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of a truncated icosahedron

• WU Name: fullerene_*
• Number of Spins: 60
• Number of Spins over all: 60
• CPU-time: ca. 1:00 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

With this calculation we want to find out the magnetic properties of an artificial magnetic molecule which is composed of 60 spins located on the vertices of a truncated icosahedron. Such a structure is known to almost everybody as it is the polyhedron which is the blueprint for a soccer ball! Moreover, in 1985 this structure has become very famous and it still is. Curl, Kroto, and Smalley (they later got the Nobel price for Chemistry for their findings) found that carbon can not only exist as graphite and diamond, but also exists in a stable form as the Fullerene C60! The Fullerene is perfectly symmetric and composed of just pentagons. Here, we study the antiferromagnetic version and want to find out its magnetic properties. We have to perform a very low temperature simulation in order to find unusual behavior like phase transitions. To do so we have to do 10.000.000 Monte Carlo steps per field value to get the necessary accuracy! Using Spinhenge@home we distribute the whole calculation using more than 100.000 work units.

60 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of a truncated icosahedron - or soccer ball (also named "Fullerene" or "Buckyball" after the famous architect Richard Buckminster Fuller).

Structure: Layered Mo₇₂Fe₃₀

• WU Name: fe30_20_x_20_fine_*
• Number of Spins: 30 / 20 x 20 (2D matrix)
• Number of Spins over all: 12.000
• CPU-time: ca. 2:00 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

This is a similar project like the fe30_20x20. By this WUs the total monte carlo cycles increased to find better conditions. This one can be charged with the old ones. So we get a better result over all.

Susceptibility measurements suggest a strong antiferromagnetic ball-to-ball interaction!


(figure by P. Kögerler)

*A. Müller et al., Solid State Sciences, Angew. Chem. 2000

Scientific Details:

• Read more about here

Structure: {Mo₇₂ Fe₃₀} - 30 paramagnetic Fe³⁺ ions (S = 5/2) embedded on the vertices of an icosidodecahedron

• WU Name: Fe30_dip_structure_*
• Number of Spins: 30
• Number of Spins over all: 30
• CPU-time: ca. 1:05 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

With this calculation we want to trace the fine structure of the susceptibility change in the Fe30 molecule when it is subject to an external magnetic field at very low temperatures. It has been found that at about 1/3 of the saturation field, which is the field where all spins are aligned parallel to the external field, a sharp resonance like anomaly appears. One can show that this anomaly is caused by the existence of 2 different types of spin configurations which become energetically competitive at 1/3 of the saturation field. However, it is totally unknown how the resonance looks like for very low temperatures and until now nobody has performed such calculations since they are very time consuming! One has to perform 3.000.000 Monte Carlo steps per field and temperature value to get the necessary accuracy! Using Spinhenge@home we distribute the whole calculation using more than 30000 work units. Our goal is to learn more about the "energy landscape" of that system at 1/3 of the saturation field for further investigations.

Exploring the fine structure of the "resonance" at 1/3 of the saturation field:

Structure: Layered Kagome

• WU Name: kagome_2_*
• Number of Spins: 30 / 100 x 100 (2D matrix)
• Number of Spins over all: 30.000
• CPU-time: ca. 2:30 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

This project is similarly kagome_100x100. On this occasion, the same qualities become an examined at another temperature and another magnetic field.

Structure: Single Dodecahedron

• WU Name: Dodecahedron_*
• Number of Spins: 20 / 1 per ball
• Number of Spins over all: 20
• CPU-time: ca. 0:20 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

This project is about the very precise calculation of the magnetic very low-temperature qualities from antiferromagnetischen Dodekaeder. Here 3 metamagnetic phase crossings are supposed, nevertheless, up to now only 2 could be found numerically, so we look for the third one! This requires a very good statistics as well as a very fine resolution with regard to the magnetic field!

• There are 3 families of possible ground states
  • a "2-0-family", a "4-0-family", and a family of umbrella-like configurations
• The umbrella family intersects both other families and therefore 2 phase transitions occur (a big one and a small one)
• Transition 1:
  • B_c,1=2.81984=0.269271 B_sat
    M_1,1=4.61556 (= magnetization before the jump)
    M_1,2=5.49239 (= magnetization after the jump)
    ?M₁=0.876828 (=height of the jump)
• Transition 2:
  • B_c,2=7.67365=0.732768 Bsat
    M_2,1=14.9208 (= magnetization before the jump)
    M_2,2=14.9862 (= magnetization after the jump)
    ?M₂=0.065408 (=height of the jump)

Structure: Layered Kagome

• WU Name: kagome_100_100_*
• Number of Spins: 30 / 100 x 100 (2D matrix)
• Number of Spins over all: 30.000
• CPU-time: ca. 2:30 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

The project calculates the magnetic qualities of a Kagome-grid consisting of 30.000 Spins. This grid is the 2-dimensional "relative" of the Fe30 ball. It is examined, on this occasion, to what extent both systems similar or even same qualities own. For this there are predictions which should be confirmed within the scope of the calculation or be disproved.

Structure: Layered Mo₇₂Fe₃₀

• WU Name: mo72_fe30_10_x_10_*
• Number of Spins: 30 / 10 x 10 (2D matrix)
• Number of Spins over all: 3.000
• CPU-time: ca. 0:40 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations:

Structure: Layered Mo₇₂Fe₃₀

• WU Name: fe30_20_x_20_1_*
• Number of Spins: 30 / 20 x 20 (2D matrix)
• Number of Spins over all: 12.000
• CPU-time: ca. 2:40 hr (old system)
  (old system: AMD XP 2600+; new system: Intel Core i5 M540 @ 2,53 GHz)

General Informations: