 # Monte Carlo Simulation of Liquid Water Daniel Shoemaker

Yüklə 476 b.
 tarix 04.02.2018 ölçüsü 476 b. #24415 • ## Write a MC liquid water simulation program from scratch which yields observables that are consistent with those found in the literature. • ## TIP3P potential:

• rOH = 0.96 Å
• HOH angle = 104.52°
• qO = -2qH = -0.834, charges located directly on atoms
• LJA = 582x103 kcal Å12/mol, LJC = 595 kcal Å6/mol • Main.h
• MC.h
• ## Source

• Main.cxx
• Coordinates.cxx
• Energy.cxx
• GofR.cxx
• MC.cxx
• MCMove.cxx
• RandGen.cxx • ## Metropolis Monte Carlo algorithm:

• Move random particle by a random distance
• Calculate ∆E
• Accept or reject move based on -1/kT
• Update position

• ## Energy data is output every 1K-10K iterations, with g(r) data recorded about as often. • ## Defining H positions without trig functions

• Use linear algebra with properly generated random numbers to position the H atoms based on O
• No lookup tables (trig functions) are used
• ## Periodic Boundary Conditions

• Setting up a 3x3x3 matrix of boxes that surround the core box is a quick way to find the shortest distance between to particles in PBC.
• Much faster than subtracting nint(distance/box)*box from the distances • ## Simulations were run with 10K initialization steps to ensure that the energy had settled. • ## g(r) does have a large initial peak, and a forbidden zone near r = 0, but its dimensions do not agree with theory • ## In this simulation, all molecules are moved after every step. • ## The g(r) normalization should be examined to correct its scale. • ## McDonald, I. R., Mol. Phys.23, 1972, 41. Yüklə 476 b.

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