So you really haven't done a MD simulation.

送交者: james_hussein_bond 于 2009-01-06, 19:54:48:

回答: 你这么看就明白了由 008 于 2009-01-06, 19:44:34:

You can implement a microscopic bit-reversible molecular dynamics (so there is no round-off error), that is in contact with a thermostat (noise source). You run the simulation for a given length of time, then reverse the simulation. The reverse simulation will track the original system back in time for a little while, then suddenly run away. The length of time it stays with the original system depends on the Liapunov exponents of the system.

This is well-documented in the literature. In fact, if you have a MD code you can do it and see it for yourself. So molecular dynamics simulations with a thermostat is inherently irreversible.

I don't care what your physics models tell you. In real life all processes happen in an environment that is similar to a thermostat. So most of these processes are also irreversible.

所有跟贴:

What do you mean by "then reverse the simulation"? - wasguru (864 bytes) 2009-01-06, 21:20:47 (291082)
- 行家一出手，便知有没有 (无内容) - ziren (0 bytes) 2009-01-06, 21:39:02 (291095)
- See this article - james_hussein_bond (626 bytes) 2009-01-06, 21:38:48 (291094)
  - 看到这句话了吗？ - wasguru (150 bytes) 2009-01-06, 21:47:31 (291096)
    - Unfortunately, the page talking about bit-MD is not visible - wasguru (244 bytes) 2009-01-08, 12:02:54 (291714)
    - Here is a book on google that has preview pages - james_hussein_bond (582 bytes) 2009-01-08, 06:58:11 (291677)
    - I don't have access to full text (无内容) - wasguru (0 bytes) 2009-01-07, 21:34:36 (291592)
    - If you simply used lattice MD, then that's true. - james_hussein_bond (226 bytes) 2009-01-07, 21:05:13 (291574)
    - Confining particles on lattice grids simply means rounding coordinates off. - wasguru (86 bytes) 2009-01-07, 20:36:24 (291560)
    - In the old days there used to be a method called lattice MD - james_hussein_bond (132 bytes) 2009-01-07, 20:29:28 (291558)
    - Discretization of what? time, or coordinates? - wasguru (72 bytes) 2009-01-07, 16:25:33 (291500)
    - According to them - james_hussein_bond (254 bytes) 2009-01-07, 16:10:21 (291489)
    - All right. Yes, for LJ(6,12), you don't have to. - wasguru (741 bytes) 2009-01-07, 15:42:40 (291471)
    - You never have to calculate square root if you use Leonard-Jones potential (无内容) - james_hussein_bond (0 bytes) 2009-01-07, 15:24:20 (291451)
    - The problem is, bit-reversible does not mean the simulation is exact - wasguru (639 bytes) 2009-01-07, 14:50:17 (291417)
    - Maybe not for you but evidently a lot of people (wink 008) - james_hussein_bond (130 bytes) 2009-01-07, 14:37:02 (291401)
    - 这样的point，还用的着他去费力气验证？ - wasguru (64 bytes) 2009-01-07, 12:54:46 (291308)
    - That's the point (无内容) - james_hussein_bond (0 bytes) 2009-01-07, 05:40:17 (291168)
- 你潜水的时间也太长久了. (无内容) - 鹏归 (0 bytes) 2009-01-06, 21:31:53 (291090)
MD simulation是什么东西我都不知道 (无内容) - 008 (0 bytes) 2009-01-06, 21:11:56 (291076)

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