Subject: Hydrocarbon Forcefields

From: Craig Burkhart <[email-masked]>
Date: Wed, 16 Oct 1996 14:29:31 -0400

Dear Netters,

I have been struggling for some time to find an appropriate molecular
forcefield for Nose'-Hoover NpT dynamics calculations on long chain
linear and branched alkanes/alkenes at liquid densities. My
selection of "appropriateness" concerns the reproduction of 300K
densities and heats of vaporization or cohesive energy densities.

I have used the all-atom OPLS (1994), the exp-6 version of DREIDING-II,
MM2, Rappe's UFF, Sybyl, Hagler's CFF-93 and the 92 version of CHARMM.
I have also used Theodorou & Suter's (1985) hybrid forcefield. All of these
well-known parameterizations do not compute the observed properties to
the degree of accuracy I require.

My queries to my net-aware colleagues:

1) Do you have experience with liquid density NpT MD simulations of
   branched hydrocarbons?
2) If so, can you point me in the direction of a forcefield which you
   have found appropriate for the calculation of liquid densities
   and delta-Hvap?

Thanks in advance. I will gladly summarize all responses for the list.

Craig

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